Gemara:

Sanhedrin 

Collections: Rabbi Meth Mini Chabura

References: Sanhedrin: 55a ,  Sanhedrin: 55b  

Description

Five factors that contribute to animals' execution: 1) concern for human dignity; 2) participation in an aveirah act; 3) deciding to do an aveirah; 4) tzeiruf to a human who is being executed for an aveirah; 5) derivation of forbidden pleasure