Sayyiduna Anas bin Malik (may Allah be pleased with him) said: Rarely did the Prophet (peace and blessings be upon him) address us without saying: "There is no faith for one who does not honour trusts, and there is no religion for one who does not keep his covenant."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوديعة / 12690