What is the ruling on the prayer of an elderly, bedridden man whose trousers are constantly wet with urine, and he prays with a urine-soaked cloth wrapped around his penis, which he is unable to change? Is his prayer permissible while he says: "Allah will forgive me because I am helpless"?

Allah does not burden a soul beyond its capacity. Thus, whoever is unable to fulfill a condition or a pillar should pray according to their situation. If your father is able to perform ablution (wudu), even with assistance, it is obligatory for him. Otherwise, he should perform tayammum (dry ablution). Due to incontinence (sals), he must perform wudu for each prayer after its time has begun, while taking precautions by tying a cloth. If he is unable to take precautions or wash away impurities, then there is no blame upon him, as avoiding impurities is waived due to incapacity. If he is able but falls short, then he should be advised gently.