It is narrated from Sayyiduna Sahl bin Sa'd al-Sa'idi (may Allah be pleased with him): "There are two times in which the gates of the heavens are opened, and very rarely is the supplication of one who supplicates rejected: at the time of the adhan, and while forming ranks in the path of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1939
Hadith Gradingمحدثین:صحيح
Hadith Takhrij«صحيح۔ أخرجه البخاري في الادب المفرد 661»