Musannaf Ibn Abi Shayba 6:1053

'Abbad ibn al-'Awwam narrated to us, from Yahya ibn Abi Ishaq, who said: I went out with Salim ibn 'Abd Allah for a funeral, and he took a path other than its [usual] path, so we intercepted him. When we reached the grave, he sat down before it was placed [in the grave].