Musannaf Ibn Abi Shayba 7:173

Abu Bakr narrated to us, he said: Abdullah ibn Idris narrated to us, from Husayn, from Abu Malik, who said: An oath that has no expiation is a man swearing to a lie intentionally. That is up to Allah; if He wills, He will punish him, and if He wills, He will forgive him.