Must a bedsheet that was washed with a handkerchief of doubtful purity be re-washed? Is the bedsheet considered impure or pure? Is it permissible to pray and sit on it?

The default state of a handkerchief is purity, and it does not become impure by being used to wipe the nose unless there is blood. Therefore, it remains pure and does not contaminate the blanket when washed with it. It is permissible to pray while wearing it or to sleep on it. One must avoid obsessive doubts (waswas), because the Sharia came with ease and to remove hardship. The default state of a person and their clothes is purity, unless one is certain that impurity has occurred, based on the saying of the Prophet, peace and blessings be upon him: "He should not depart until he hears a sound or perceives a smell."