Brewer's: Crocodile's Tears
Hypocritical tears. The tale is, that crocodiles moan and sigh like a person in deep distress, to allare travellers to the spot, and even shed tears over their prey while in the act of devouring it.
As the mournful crocodile With sorrow snares relenting passengers.
Shakespeare: 2 Henry VI., iii. 1.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894