A woman used to pray behind the Prophet ﷺ who was beautiful, among the most beautiful of people. Some of the men would press forward to be in the first row so as not to see her, while others would hold back so as to be in the last row, and when such a man bowed, he would do like this, peering out from beneath his armpit. So Allah revealed, concerning her, "And We certainly know those among you who go forward, and We certainly know those who lag behind" [Hijr 15:24].
حدثنا حميد بن مسعدة وأبو بكر بن خلاد قالا حدثنا نوح بن قيس حدثنا عمرو بن مالك عن أبي الجوزاء
كانت امرأة تصلي خلف النبي ﷺ حسناء من أحسن الناس فكان بعض القوم يستقدم في الصف الأول لئلا يراها ويستأخر بعضهم حتى يكون في الصف المؤخر فإذا ركع قال هكذا ينظر من تحت إبطه فأنزل الله {ولقد علمنا المستقدمين منكم ولقد علمنا المستأخرين} في شأنها
[Its chain of transmission is daif] Tirmidhi recorded it in the tafsir of the Quran, the chapter on Surah Hijr, hadith no. 3122, from the hadith of Nuh through this route.Amr bin Malik Nakri is graded daif by Bukhari (Tahdhib al-Tahdhib, 1/336), and Ibn Hibban alone rated him trustworthy, while still saying he makes mistakes and reports unusual material. Ibn Adi said regarding Abu Jawza that Amr bin Malik related about ten hadiths from him that are not preserved.