It is narrated from Sayyiduna Sahl bin Sa’d (may Allah be pleased with him), he said: The gates of the heavens are opened at two times, and the supplication of the one who supplicates is rarely rejected: when the call to prayer (adhan) is given, and when ranks are formed in the path of Allah against the enemy.
Hadith Referenceالادب المفرد / كتاب / 661
Hadith Gradingالألبانی:صحيح موقوفًا وهو فى حكم المرفوع وقد صح مرفوعًا
Hadith Takhrij«صحيح موقوفًا وهو فى حكم المرفوع وقد صح مرفوعًا : أخرجه مالك فى الموطأ : 70/1 و الدارمي : 766/2 موقوفًا ، و رواه أبوداؤد : 540 مرفوعًا - انظر صحيح الترغيب : 266»
Explanation & Benefits
Shaykh Maulana Usman Muneeb
Benefits and Issues: This narration is also authentically established as marfu‘ (attributed to the Prophet), (Sahih Sunan Abi Dawud, Hadith: 2290). Therefore, these two times should be considered precious, and one should make abundant supplication during them. In addition to these, supplications are certainly accepted between the adhan and iqamah, in the last part of the night, after ‘Asr on Friday, at the time of rainfall, and during travel.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 661