Does any how Vinaya pitak contradicts

As Iโ€™m in a debate where people from other religion attack on buddha on the basis of vinaya pitak so I just want to prove that vinay pitak is not words of buddha as many things contradicts
For example: buddha says about giving of four filthy things to snake bite as treatment but in angutar nikaya Ahi sutta buddha gives a metta chanting of four royal snake as protection from snakes isnโ€™t contradicts
Can anyone provide some sutta that contradicts vinay pitak

The sutta teaching is about how to avoid being bitten by snakes and the vinaya teaching is about how to treat yourself if you do get bitten. Whereโ€™s the contradiction here? Would a doctor be contradicting himself if he advised you on both the precautions to avoid catching malaria and the medicines to take if you happen to catch it anyway?