Hadith #847 (Sunan al-Nasa'i)
Book: The Book of Leading the Prayer (Al-Imamah)
Narrator(s): Abdullah bin Mubarak عبد الله بن المبارك, al-Sa'ib bin Hbysh السائب بن حبيش, Ma'dan bin Abi Talha معدان بن أبي طلحة ويقال بن طلحة, Swyd bin Nsr bin Swyd سويد بن نصر بن سويد, Za'ida bin Qadama al-Thaqifi زائدة بن قدامة الثقفي

“The Messenger of Allah (ﷺ) turned to face us when he stood up to pray, before he said Takbir, and said: ‘Make your rows straight and fill the gaps, for I can see you from behind my back.”‘

Source: https://parallelquran.com/hadith/sunan-al-nasai-847/