Scriptural Documentation on the sin nature of oral sex.
The bible tells us that we are to come with two or three witnesses {Deuteronomy 19:15}. The word of God is infallible meaning that it is positive proof for righteous living on earth.
The first witness is that the Lord places the seed of the man in his loins { exodus 12:11; 1Kings 8:19}. The seed of the man is to reproduce {Genesis 9:9). The seed/semen of a man is given to him by God to serve a purpose. When the seed is misplaced (Genesis 38:8-10) God has a justified right to kill you.
Second Witness; the word of the Lord tells us that our tongue is a an unruly member; making all of our body parts members {Roman 6:13; Matthews 5:29-30}. So if our tongue is for speaking then are reproductive organs have a purpose as well. And that purpose is for reproducing, which is why the word of God tells us that our members are yielded to God for His righteousness and for His glory. Meaning that He created them to be used in the right way using them in the wrong way is unrighteous and unholy, which is an abominations to God. Meaning He will cast you out, and away. EBH