Is it permissible to combine and shorten prayers in Moscow when the duration of stay is not determined, and is it permissible to pray sitting on the bed while performing the standing and prostration gestures upon it, or is it obligatory to perform the correct standing, or to pray standing and sit on a chair for prostration?

The majority of scholars hold that the duration of stay that permits a traveler to avail themselves of the concessions of travel is less than four days, or twenty prayers. Therefore, whoever intends to stay in a country for more than this period is not allowed to shorten (qasr) or combine (jam') prayers. As for one who intends to stay for less than four days, or is undecided about the duration of their stay, they are permitted to shorten and combine prayers, even if their stay prolongs, as long as they have not definitively intended to stay for four days or more.