Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that a man was praying with his waist-wrapper hanging below his ankles, and the Messenger of Allah (peace and blessings be upon him) said to him: "Go and perform ablution." The man went, performed ablution and came back, and he (peace and blessings be upon him) said: "Go and perform ablution." The man went, performed ablution again and came back. Then a man asked him (peace and blessings be upon him): "O Prophet of Allah! Why did you order him to perform ablution and then remain silent about him?" He (peace and blessings be upon him) said: "He was praying with his waist-wrapper hanging below his ankles, and Allah Almighty does not accept the prayer of one who prays with his waist-wrapper hanging down."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3304
Ata' bin Yasar (may Allah have mercy on him) narrates that one of the Companions (may Allah be pleased with him) of the Messenger of Allah (peace and blessings be upon him) narrated to him: Once we were sitting with the Messenger of Allah (peace and blessings be upon him) when a man came and began to pray, and the Messenger of Allah (peace and blessings be upon him) said to him: "Go and perform ablution." He performed ablution and then began praying again, and the Messenger of Allah (peace and blessings be upon him) again said to him: "Go and perform ablution." A man said: "O Messenger of Allah! What is the reason that you order him to perform ablution and then remain silent?" He (peace and blessings be upon him) said: "I told him to perform ablution only because he was praying with his waist-wrapper hanging below his ankles, and Allah Almighty does not accept the prayer of one who prays with his waist-wrapper hanging below his ankles."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3305
It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that he saw a Bedouin wearing a sheet who was praying with it hanging below his ankles, and he said: "Whoever lets his waist-wrapper hang below his ankles in prayer out of arrogance, for such a person Allah Almighty will neither make Paradise lawful nor Hell unlawful."
Imam Abu Dawud (may Allah have mercy on him) states that a group of narrators reported this hadith from Asim as mawquf (stopping) at Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him); among them are Hammad bin Salamah, Hammad bin Zayd, Abu al-Ahwas and Abu Mu'awiyah (may Allah have mercy on them).
The Imam says that the established, unqualified hadiths forbidding the trailing of the waist-wrapper are evidence that it is disliked (makruh), both in prayer and at other times.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3306