It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that a man asked him which deed is the most virtuous. He said: "Remembering Allah, the Mighty and Majestic," and then he said 'Allahu akbar' (Allah is the Greatest) three times.
Then he said: "No people sit in one of the houses of Allah, the Blessed and Exalted (a mosque), studying the Book of Allah Almighty together and teaching it to one another, except that the angels shade them with their wings, and they remain the honoured guests of Allah, the Blessed and Exalted, until they get up from there."
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب الأذكار والدعوات / 3391
Hadith Gradingمحدثین:إسناده صحيح
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :إسناده صحيح إلى ابن عباس رضي الله عنهما، ومثله له حكم الرفع. » «أخرجه مسند الدارمي برقم: 357، وأخرجه المطالب العالية لابن حجر برقم: 3021، وأخرجه مصنف ابن أبي شيبة برقم: 26638»