Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Beware of trivial deeds, for if they accumulate upon a man, they will destroy him." The Prophet (peace and blessings be upon him) gave a parable for them: "Like a people who are in a barren desert, and the time for the people's cooking comes; so the people begin to bring one stick at a time, until they have gathered many sticks; then they light a fire, and it burns whatever is thrown into it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20762