Musannaf Ibn Abi Shaybah 12145 — Reports on greeting the graves when

Musa bin Uqbah said: I saw Salim bin Abdullah: whether by day or by night, whenever he passed by a grave he would greet it with salam, while we were travelling with him. He would say: 'Al-salamu alaykum' (Peace be upon you). I asked him about it, and he told me that his father used to do so.