Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: A very beautiful woman used to perform prayer behind the Prophet Muhammad (peace and blessings be upon him). Some of those present would stand in the first row so that they would not see her, and some people would stand in the last row so that when they went into bowing (ruku‘), they could look at her from under their armpits. So Allah Almighty revealed this verse regarding this: "And We surely know those of you who go forward and those who lag behind."
Hadith Referenceصحیح ابن حبان / كتاب البر والإحسان / 401
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «الصحيحة» (2472).فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده حسن، من أجل عمرو بن مالك -وهو النكري- فإنه صدوق له أوهام، وباقي رجاله على شرط مسلم. أبو الجوزاء: اسمه أوس بن عبد الله الربعي، روى له الجماعة.