It is narrated from Hazrat Bara’ (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Whoever says these words: "La ilaha illallah wahdahu la sharika lahu, lahul mulk wa lahul hamd wa huwa ‘ala kulli shay’in qadeer" — it is like freeing a slave. Whoever gives someone a gift, such as silver or gold, or gives someone milk to drink, or gives someone a water-skin, it is as if he has freed a slave.
Hadith Referenceمسند احمد / أول مسند الكوفيين / 18531