What is the ruling on wearing loose trousers during prayer?

A man's prayer is valid in loose-fitting trousers if they cover what is between the navel and the knee and are not transparent. It is preferable to wear a shirt over them that covers what is between the navel and the knee and extends to mid-calf or the ankle for complete coverage. Praying in a covering loincloth (izar) is better than praying in trousers without a covering shirt because it offers more concealment. The worshipper should adorn himself for prayer, as Allah Almighty says: (O Children of Adam, take your adornment at every place of prayer) (Quran 7:31). The more complete his appearance, the greater his reward.