Shalom All,
    This is a hyper-link to a very interesting Temple Service.  Read it, then evaluate it according to some of the facts in it.

http://www.lttn.org/R5_Article3_LeviticalChoir.htm

   I think it really unusual, that on Shabbat they sang the 92nd Psalm...but on the 9th. of Av...which the article relates was:
    When the TEMPLES (plural)  and the city of Jerusalem were destroyed..it was on the 9th. of Av, and a Shabbat.
    Yet, the song for those dates that was sung, was the song of Wednessday, the 94th. Psalm...and it is the song for the 7th. Melinium.
    The article says that the weekly weekday songs also represented the Melinium.
     So Why is the song for the "Day of the Lord" His Shabbath, the song sang on Wednessday?
    And what about the fast of the 9th. of Av, falling on a Shabbat?  Usually, when a fast falls on a Shabbat, the calendar is adjusted so that does not happen, yet twice on the 9th. of Av...it apparently fell on Shabbat.
    Makes the verse of scripture that says we are to pray that the Day of The Lord, does not come in winter or on a Shabbat.....a little deeper study.

Shalom,
Meriam Brown