Is a man's penis considered impure after intercourse, requiring immediate washing before sleep? And should clothes touched by the penis be washed if penetration occurred without a barrier due to a woman's secretions, or is this an excessive burden not mentioned by the Prophet (peace be upon him), especially since it was narrated that semen should be rubbed off clothes?

The most authoritative opinion is that semen is pure and does not require washing. If a man has intercourse with his wife without a barrier, his penis is not considered impure, even if it comes into contact with the wife's secretions, because these secretions are considered pure by some scholars, and the presence of madhy (pre-seminal fluid) is not certain. In this case, there is no obligation to wash the penis, and anything it touches, such as clothing, does not become impure. The default is purity until certainty of impurity is established. Doubt about mixing does not harm, because the default is purity. Moreover, assuming possibilities in such matters can lead to waswasah (obsessive whispering/doubts).