Abu Saeed Khudri reported,

The Messenger of Allah ﷺ said, "How can I take comfort when the bearer of the trumpet has already placed it to his lips and bowed his forehead, waiting for the command to blow?"The companions asked, "Messenger of Allah, what should we say on that day?"He replied, "Say, 'Allah is sufficient for us and the best disposer of affairs. Upon Allah we rely.'"

Azami 952

Sahih

عن أبي سعيد الخدري قال

قال رسول الله ﷺ: كيف أنعم وصاحب الصور قد التقم، وحنا جبهته ينتظر متى يؤمر أن ينفخ. قيل: قلنا يا رسول الله، ما تقول يومئذ؟ قال: قولوا: حسبنا الله ونعم الوكيل على الله توكلنا.

الأعظمي 952صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Faith
Chapter
Belief in the Last Day
Section
Blowing of the trumpet
Numbering
Jami al-Kamil 952 (2nd edition)
Azami 952