It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him); he said: The first to pray with the Prophet (peace and blessings be upon him) was Ali (may Allah be pleased with him). (The narrator says:) I told this to Ibrahim, and he rejected it and said: "The first to pray was Abu Bakr (may Allah be pleased with him)."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4983