Jamiat Tirmidhi: Hadith 3771

“Whoever says ten times: ‘None has the right to be worshipped by Allah, Alone, without partner, to Him belongs all that exists, and to Him belongs the praise, [He gives life and causes death,] and He has power over all things, (Lā ilāha illallāh, waḥdahu lā sharīka lahu, lahul-mulku wa lahul-ḥamdu, [yuḥyī wa yumītu,] wa huwa `alā kulli shai’in qadīr)’ it is for him equal to freeing four slaves among the offspring of Isma`il.”