Musnad Ahmad 1475

It was narrated from "Abdullah bin Abi Salamah (رضي الله عنه) that Sa"d (رضي الله عنه) heard a man saying Labbaika Dhul-Ma"arij (here I am at Your service, Lord of the ways of ascent). He said: “He is indeed the Lord of the ways of ascent, but we were with the Messenger of Allah (ﷺ) and we did not say that.”