عن إبن عباس قال كانت إمرأة تصلي خلف رسول الله ﷺ حسناء من أحسن الناس فكان بعض القوم يتقدم حتى يكون في الصف الأول لئلاً يراها ويستأخر بعضهم حتى يكون في الصف المؤخر فإذا ركع نظر من تحت إبطيه فأنزل الله ﴿ ولقد علمنا المستقدمين منكم ولقد علمنا المستأخرين ﴾ قرآن
جامع الترمذي كتاب التفسير
From Ibn ‘Abbas who said: A certain woman used to pray behind the Messenger of Allah (SAW), radiantly beautiful, among the most beautiful of people. Some of those present would advance so that they would be in the first row, lest they see her, while others would move back so that they would be in the last row; and whenever He bowed down, He would glance under His armpits; so Allah sent down { We have known those of you who seek to go in front, and We have known those of you who seek to go behind } [Al-hijr 24].
Sunan Al-Tirmidhi, The book of tafsir