Abu Hurairah (May Allah be pleased with him) reported:
Messenger of Allah ﷺ said to a man who was performing Salat while his lower garment was trailing, "Go and perform your Wudu' again." That man went and came back having performed it. The Messenger of Allah ﷺ said (again), "Go and perform your Wudu'." Someone present said to Messenger of Allah ﷺ: "O Messenger of Allah! You ask him to perform his Wudu' and then you kept silent (without saying the reason for it)." He ﷺ said, "He performed Salat while his lower garment was below his ankels. Allah does not accept the Salat of a man who trails his lower garment."

[Abu Dawud].

وعن أبى هريرة رضى الله عنه قال: بينما رجل يصلى مسبل إزاره، قال له رسول الله ﷺ: "اذهب فتوضأ" فذهب فتوضأ، ثم جاء فقال :" اذهب فتوضأ" فقال رجل يا رسول الله ما لك أمرته أن يتوضأ ثم سكت عنه؟ قال: "إنه كان يصلى وهو مسبل إزاره، وإن الله لا يقبل صلاة رجل مسبل".