Is it permissible to fast Saturday alone as a day in lieu?

The majority of scholars hold the view that it is disliked to single out Saturday for voluntary fasting, basing their opinion on the Prophet's (peace be upon him) saying: "Do not fast on Saturday unless it is for what has been made obligatory upon you." Scholars have, however, made an exception for fasting done to make up missed fasts (qada'), fulfill a vow (nadhr), or for a regular devotional fast (wird), and the like.