This view is narrated from Alqamah, al-Aswad, Suwayd bin Ghafalah, Ata, Tawus, Mujahid, Salim, al-Qasim and al-Hasan al-Basri (may Allah have mercy on them); they said: "The imam (ruler) will step forward (to lead the funeral prayer)."
It is also narrated from Sayyiduna Ali (peace be upon him) and Sayyiduna Jarir bin Abdullah (may Allah be pleased with him), but it is not established from either of them; however, it is well known from Sayyiduna al-Husayn bin Ali (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / Q6894