Ibn Hibban

Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) said: "How can I remain at ease when the one assigned to blow the trumpet has already placed his mouth upon it and has bent his forehead, waiting for the command as to when he should blow?" The narrator says: We said, "O Messenger of Allah! What should we say on that day?" The Prophet (peace and blessings be upon him) said: "You should say: «حَسْبُنَا اللهُ وَنِعْمَ الْوَكِيلُ» (Allah is sufficient for us and He is the best disposer of affairs)."
(Imam Ibn Hibban, may Allah have mercy on him, says:) Abu Ya'la has narrated a similar report with his chain, but he has transmitted these words: «حَسْبُنَا اللَّهُ وَنِعْمَ الْوَكِيلُ», «عَلَى اللَّهِ تَوَكَّلْنَا» "You should say: Allah is sufficient for us and He is the best disposer of affairs, and upon Allah alone do we rely."