Anas (May Allah be pleased with him) reported:
When the Iqamah had been announced, the Messenger of Allah (ﷺ) turned his face towards us and said: "Make your rows straight and stand close together, for I can see you from behind my back."[Al- Bukhari].
App reference: Book 9, Hadith 98
Arabic/English book reference: Book 9, Hadith 1088