Numbers 20 et seq.
Here you see Balaam get a very clear word from the Lord telling him what not to do. Yet, when more worldly honor and money were shown to him, he determined to go and tried to get God to bless it. It did not turn out well.
I have had people tell me they knew what the Bible said on a subject, but they had prayed and were sure God would let them do what they wanted to do. It is important to seek our answers by the Bible where they are given, then to be a "doer of the word". (James 1:22)
Our feelings are not good guides to God's will, for they are tainted by our desires. Jeremiah 17:9 says the heart is deceitful above all things. Even David, the man after God's own heart, surrendered to his flesh and sinned greatly.
If God has spoken in the Bible, he will not contradict it in prayer. Do what he says to do. Refrain from doing what he forbids. In all your ways acknowledge him and he will keep your paths straight. (Proverbs 3:6)
And remember, even the guy who wrote that (Solomon) did not take his own advice and fell into sin. Let's be careful out there.