Abu Musa Ashari reported,

The Messenger of Allah ﷺ addressed us, explaining our way of life and teaching us our prayer. Among the things he said was, "When you pray, straighten your rows, then let one of you lead you. When he says the takbir, say the takbir. When he recites, 'not of those who have earned Your anger, nor of those who have gone astray,' say 'Ameen,' and Allah will respond to you."He then mentioned the rest of the hadith in its full length.

Azami 1972

Sahih

عن أبي موسى قال

خطبنا رسول الله ﷺ فبين لنا سنتنا، وعنمنا صلاتنا وقال فيما قال: إذا صليتم فأقيموا صفوفكم، ثم ليؤمكم أحدكم، فإذا كبر فكبروا، وإذا قال: غير المغضوب عليهم ولا الضالين، فقولوا: آمين، يجبكم الله… فذكر الحديث بطوله.

الأعظمي 1972صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Prayer
Chapter
Description of prayer, the takbir, standing, and recitation
Section
Obligation of reciting Surah Fatihah
Numbering
Jami al-Kamil 1972 (2nd edition)
Azami 1972