It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "How can I be at ease when the angel of the Trumpet has put the Trumpet to his mouth, waiting for when he will be commanded to blow into it?" The Companions said: Then what should we say? He said: "Say: Hasbuna Allahu wa ni'ma al-wakil (Allah is sufficient for us, and He is the best Disposer of affairs)."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5053