Musannaf Ibn Abi Shayba 37:314

Waki’ narrated to us, from Malik ibn Mighwal, from al-Qasim ibn ‘Abd al-Rahman, who said: ‘Abdullah said: "Indeed, a man witnesses a sin and disapproves of it, so he is like one who was absent from it. And a man is absent from it, but he is pleased with it, so he is like one who witnessed it."