I saw Ali (Allah be pleased with him) catching hold of his left hand) by his right hand on the wrist above the navel.

Abu Dawud said: Sa'id b. Jubair narrated the words: "above the navel". Abu Mijlaz reported the words: "below the navel". This has also been narrated by Abu Hurairah. But that is not strong.
Sunan Abi Dawud Book 2, Hadith 367