Is a man required to serve on the High Council before he is considered a candidate for the calling of Bishop? I was advised by a member of the High Council that Bishops are almost always required to sit as a High Councilman before he is considered. If so, where in the scriptures is this instruction found?
There is no scriptural requirement for a Bishop to sit on a High Council first.
There are some practical considerations that your High Councilman may have noticed that might make a High Councilman a higher possibility.
Let’s see if I can help you understand why that is.
Calling a Bishop is an important and profound event that a Stake President should do with all solemnity and prayer. It is possible that while a Stake President is pondering whom to call, the name of a complete and total stranger will be given him by the Lord. This would be quite rare. Most of the time that does not happen, and the Stake President is under the same instructions regarding gaining revelations that the Lord gave to Oliver Cowdery in D&C 9:8,
8 But, behold, I say unto you, that you must study it out in your mind; then you must ask me if it be right, and if it is right I will cause that your bosom shall burn within you; therefore, you shall feel that it is right.
The Stake President must study out potential Bishops. He must have or gain a feel for these men and their character and make a judgment on whether or not he thinks they would make a good Bishop. If he thinks so, then he must pray and ask the Lord “if it be right” and await the Lord’s answer.
For practical purposes it’s going to be someone the Stake President knows and trusts (unless the Lord is very clear otherwise). The High Council is a collection of people the Stake President knows and has worked with. He will learn a lot about them while working with them on the duties of the High Council. He will be able to “study them out in his mind”.
So while there is no scriptural requirement that a Bishop serve on a High Council first, the High Council is a logical and reasonable place for the Stake President to look for future Bishops. Of course the Stake President is not limited to the High Council by any means. As long as he can “study them out” he can look anywhere for someone who meets the requirements for a Bishop.