Musnad Ahmad 626:18

Hashim ibn al-Qasim narrated to us, Sharik narrated to us, from 'Abd al-Malik ibn 'Umayr, from Husayn, from al-Mughirah ibn Shu'bah, who said: I saw the Prophet, peace and blessings of Allah be upon him, take hold of the waist-wrapper (hujzah) of Sufyan ibn Abi Sahl while he was saying: "O Sufyan ibn Abi Sahl, do not let your lower garment trail, for Allah does not love those who let their garments trail."