Sayyiduna Jarir bin Abdullah (may Allah be pleased with him) narrates that I pledged allegiance to the blessed hand of the Messenger of Allah (peace and blessings be upon him) on establishing prayer, giving zakat, and being sincere to every Muslim.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب التغليظ فى منع الزكاة / 2259