A week ago I was reading Matthew, and at Mt 2:15 and 2:17 he write about Old Testament prophecies. Searching for it, maybe in Jeremiah, I read something like 'we must be cautious reading the Holy Scriptures because prophets can make mistakes'. I found it a beautiful message, but at the time, when I was searching for the prophecy referenced by Matthew, I don't pay too much attention to it, and today I'm not able to find it again. Can someone point me the location of some versicle that could be that?
I think the passage you are asking about is:
Jeremiah 14:13 through 17 KJV Then said I, Ah, Lord GOD! behold, the prophets say unto them, Ye shall not see the sword, neither shall ye have famine; but I will give you assured peace in this place. 14 Then the LORD said unto me, The prophets prophesy lies in my name: I sent them not, neither have I commanded them, neither spake unto them: they prophesy unto you a false vision and divination, and a thing of nought, and the deceit of their heart. 15 Therefore thus saith the LORD concerning the prophets that prophesy in my name, and I sent them not, yet they say, Sword and famine shall not be in this land; By sword and famine shall those prophets be consumed. 16 And the people to whom they prophesy shall be cast out in the streets of Jerusalem because of the famine and the sword; and they shall have none to bury them, them, their wives, nor their sons, nor their daughters: for I will pour their wickedness upon them. 17 Therefore thou shalt say this word unto them; Let mine eyes run down with tears night and day, and let them not cease: for the virgin daughter of my people is broken with a great breach, with a very grievous blow.
If this is the passage it must be noted that it is referring to False Prophets as stated in verse 14.
If these are not the verses you are asking about let me know and I will do some more research.
Hope this helps.
I can't think of any passage where God (through the inspired writers of the Bible) would be saying that true prophets of God or the written word of God itself might be mistaken, so you should pick and choose carefully what you believe.
Here's a list of all word forms of "prophet" or "prophecy" from Jeremiah. You'll notice that the theme of almost all these verses is God's condemnation of all the false prophets of Judah. Time and time again God warns his people not to listen to them because He has not sent them. The clear implication is that true prophets, like Jeremiah, prophecy the true word of God, and therefore refusing to believe them would be foolish.
In fact one of the signs of a true prophet of God is that what he prophecies comes true. A prophecy that does not come true is a sign of a false prophet. Read about Jeremiah's encounter with Hananiah in Jeremiah 28 to see how that played out, especially verse 9:
As for the prophet who prophesies peace, when the word of that prophet comes to pass, then it will be known that the LORD has truly sent the prophet.” (Jeremiah 28:9 ESV)