Sayyiduna Abdullah bin Anis (may Allah be pleased with him) narrates that the Prophet Muhammad (peace and blessings be upon him) said: "Among the major sins are associating partners with Allah, disobeying parents, and taking a false oath. By the One in Whose hand is my soul! If a person swears an oath about anything, even as small as a mosquito's wing, then on the Day of Resurrection that oath will be a burden (or a stain) upon his heart."