釈迦に説法 (しゃかにせっぽう): lecturing to the Buddha; teaching something to someone who knows more than you; teaching your grandmother to suck eggs
釈迦に説法
lecturing to the Buddha; teaching something to someone who knows more than you; teaching your grandmother to suck eggs
Preaching Buddhist doctrine to the Buddha. Most often used as a pre-emptive apology, just before explaining something to someone who plainly knows it already.
The same saying in Chinese: 班门弄斧