It is narrated from Hazrat Sahl (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Beware even of minor and insignificant sins, for their example is like that of people who camped in a valley; one person brought a stick, another brought another stick, and in this way they gathered enough to bake their bread. And when a person is taken to account for insignificant sins, they will destroy him."
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 22808