Where in the Bible does it say "my thoughts are not your thoughts"?

In the book of Isaiah we find these words from the LORD.

In Isaiah 55:8For my thoughts are not your thoughts, neither are your ways my ways, saith the LORD.
See All... we find the phrase "my thoughts are not your thoughts."

"My thoughts are nothing like your thoughts," says the Lord. "And my ways are far beyond anything you could imagine. ( New Living Translation )

"For My thoughts  are  not your thoughts, Nor  are  your ways My ways," says the Lord. ( New King James Version )

"My thoughts," says the Lord, "are not like yours, and my ways are different from yours. ( Good News Translation )

Our Bible Commentary   says this about Isaiah 55:

Chapter 55 begins with the analogy cited by Jesus in the New Testament of the water of life—the Holy Spirit (see John 4:10-14 [10] Jesus answered and said unto her, If thou knewest the gift of God, and who it is that saith to thee, Give me to drink; thou wouldest have asked of him, and he would have given thee living water.
[11] The woman saith unto him, Sir, thou hast nothing to draw with, and the well is deep: from whence then hast thou that living water?
[12] Art thou greater than our father Jacob, which gave us the well, and drank thereof himself, and his children, and his cattle?
[13] Jesus answered and said unto her, Whosoever drinketh of this water shall thirst again:
[14] But whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life.

See All...; John 7:37-38 [37] In the last day, that great day of the feast, Jesus stood and cried, saying, If any man thirst, let him come unto me, and drink.
[38] He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water.

See All...; Revelation 21:6And he said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely.
See All...; Revelation 22:1And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb.
See All..., Revelation 17). This ties back to earlier references in Isaiah, such as Isaiah 12:3Therefore with joy shall ye draw water out of the wells of salvation.
See All... and Isaiah 44:3For I will pour water upon him that is thirsty, and floods upon the dry ground: I will pour my spirit upon thy seed, and my blessing upon thine offspring:
See All.... We are told to buy even though we have no money. It is a totally free gift—albeit a gift with conditions. God requires only true repentance accompanied by faith and then baptism (see Acts 2:38Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
See All...; Hebrews 11:6But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him.
See All...). Of course, what many do not understand is that repentance is more than just being sorry for past sins. It also involves a lifelong commitment to obeying God.

"Wine and milk [in Isaiah 55:1Ho, every one that thirsteth, come ye to the waters, and he that hath no money; come ye, buy, and eat; yea, come, buy wine and milk without money and without price.
See All...] are symbols of complete satisfaction ( Isaiah 55:2Wherefore do ye spend money for that which is not bread? and your labour for that which satisfieth not? hearken diligently unto me, and eat ye that which is good, and let your soul delight itself in fatness.
See All...). Not only does God's salvation supply what is necessary for life, but it also provides what brings joy" ( Nelson Study Bible,  note on verse 1). As Jesus said, "I have come that they may have life, and that they may have it more abundantly" (John 10:10The thief cometh not, but for to steal, and to kill, and to destroy: I am come that they might have life, and that they might have it more abundantly.
See All...)—meaning now and on into eternity beyond. "Abundance" is directly mentioned in verse 2 of Isaiah 55. Notice also that the invitation to "eat" and "delight" in abundance can be likened to a banquet. Jesus gave parables that picture salvation as partaking of a banquet (see Matthew 8:11And I say unto you, That many shall come from the east and west, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven.
See All...; Luke 14:15-24 [15] And when one of them that sat at meat with him heard these things, he said unto him, Blessed is he that shall eat bread in the kingdom of God.
[16] Then said he unto him, A certain man made a great supper, and bade many:
[17] And sent his servant at supper time to say to them that were bidden, Come; for all things are now ready.
[18] And they all with one consent began to make excuse. The first said unto him, I have bought a piece of ground, and I must needs go and see it: I pray thee have me excused.
[19] And another said, I have bought five yoke of oxen, and I go to prove them: I pray thee have me excused.
[20] And another said, I have married a wife, and therefore I cannot come.
[21] So that servant came, and shewed his lord these things. Then the master of the house being angry said to his servant, Go out quickly into the streets and lanes of the city, and bring in hither the poor, and the maimed, and the halt, and the blind.
[22] And the servant said, Lord, it is done as thou hast commanded, and yet there is room.
[23] And the lord said unto the servant, Go out into the highways and hedges, and compel them to come in, that my house may be filled.
[24] For I say unto you, That none of those men which were bidden shall taste of my supper.

See All...). Isaiah 55:2Wherefore do ye spend money for that which is not bread? and your labour for that which satisfieth not? hearken diligently unto me, and eat ye that which is good, and let your soul delight itself in fatness.
See All... mentions the bread analogy used by Jesus as well (see John 6:48-58 [48] I am that bread of life.
[49] Your fathers did eat manna in the wilderness, and are dead.
[50] This is the bread which cometh down from heaven, that a man may eat thereof, and not die.
[51] I am the living bread which came down from heaven: if any man eat of this bread, he shall live for ever: and the bread that I will give is my flesh, which I will give for the life of the world.
[52] The Jews therefore strove among themselves, saying, How can this man give us his flesh to eat?
[53] Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you.
[54] Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day.
[55] For my flesh is meat indeed, and my blood is drink indeed.
[56] He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him.
[57] As the living Father hath sent me, and I live by the Father: so he that eateth me, even he shall live by me.
[58] This is that bread which came down from heaven: not as your fathers did eat manna, and are dead: he that eateth of this bread shall live for ever.

See All...).

Verse 3 of Isaiah 55 mentions the "sure mercies of David" (Isaiah 55;3). Paul explained in his speech at Antioch of Pisidia in Acts 13:34And as concerning that he raised him up from the dead, now no more to return to corruption, he said on this wise, I will give you the sure mercies of David.
See All... that this referred to Jesus being raised from the dead, and he goes on to cite Psalm 16 of David, which is full of many promises of future inheritance, blessings and pleasures. These "sure mercies" are also described here as an "everlasting covenant" that God is willing to make with all who "thirst" and come to God. And David was a witness of these promises (Isaiah 55:4Behold, I have given him for a witness to the people, a leader and commander to the people.
See All...). Indeed, there may also be a reference here to the Davidic covenant itself—wherein God promised David an eternal offspring, throne and kingdom. This, of course, is ultimately fulfilled in Christ—who was destined to inherit the throne of David. Yet this promise is for us as well—since Jesus said that His followers would share His throne with Him (see Revelation 3:21To him that overcometh will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne.
See All...; compare Romans 8:17And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.
See All...).

Isaiah 55 goes on to say that even the wicked may seek and find God if they forsake their wrong way and "return" to Him—the Old Testament term for repent. God says He will have mercy, immediately followed by a statement that His thoughts and ways are higher than  our thoughts and ways. In its note on Isaiah 55:6-7 [6] Seek ye the LORD while he may be found, call ye upon him while he is near:
[7] Let the wicked forsake his way, and the unrighteous man his thoughts: and let him return unto the LORD, and he will have mercy upon him; and to our God, for he will abundantly pardon.

See All...,  The Bible Reader's Companion  states: "It is in the free pardon that God offers the wicked that the sharpest difference between God's thoughts and our thoughts are seen. We feel anger and outrage and call for revenge. God feels compassion and love and extends mercy. Thus God's word is gentle and life-giving; in Isaiah's analogy, like the gentle rain that waters the earth and causes life to spring up. What a warm and wonderful view of God (Isaiah 55:10For as the rain cometh down, and the snow from heaven, and returneth not thither, but watereth the earth, and maketh it bring forth and bud, that it may give seed to the sower, and bread to the eater:
See All...)."

The chapter ends with God's people leaving their exile. Again, this should be understood as having multiple applications: the Jews leaving Babylonian captivity; Israel and Judah leaving their end-time captivity; spiritual Israel receiving its deliverance through Christ today; the ultimate deliverance of spiritual Israel in its glorification at Christ's return; the spiritual deliverance of physical Israel and all mankind when they are joined to spiritual Israel through Christ; and finally their ultimate deliverance when they are glorified as well. Commentators explain this chapter as being the last one addressed to the people in captivity. The remaining chapters of Isaiah are claimed by many to be addressed to a post-exilic audience.