Riyad as-Salihin, Book 12, Hadith 1325 (In-Book) ⓘ
Sahl bin Sa'd (May Allah be pleased with him) reported: The Messenger of Allah said, "Supplications at two times are never turned down (or said, "Are seldom turned down"), a supplication after the Adhan has been proclaimed, and a supplication during the battle combating the enemy."[Abu Dawud].
وعن سهل بن سعد رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم "ثنتان لا تردان، أو قلما تردان: الدعاء عند النداء وعند البأس حين يلحم بعضهم بعضًا" ((رواه أبو داود بإسناد صحيح)).