What is the ruling on clothes worn without istinja' (purification after defecating or urinating) while having hair (on them)?

Ablution (istinja') and the removal of impurities from the body and clothing are conditions for the validity of prayer. Neglecting ablution for one who intends to pray is a grave sin, and many scholars have considered it among the major sins. Al-Dhahabi narrated from the Prophet, peace and blessings be upon him, that he said: "Cleanse yourselves from urine, for indeed the general torment of the grave is due to it."

Therefore, one must repent from neglecting ablution, and prayer is not valid without it, because avoiding impurities is a condition for the validity of prayer. As for clothing, any impurity that has affected it must be washed before prayer, in accordance with the Almighty's saying: "{And purify your garments}" (74:4). If you doubt whether an impurity has reached the garment, the default is that it is pure, and it should not be judged impure except with certainty.