Gemara:

Rosh Hashana 

Halacha:

Rosh Hashana,  Tefillah 

Mishna:

Rosh Hashana 

Collections: R' Grunstein Shir Shel Yom at Mincha

References: Rosh Hashana: 31A  

Description

Why don't we say Shir Shel Yom at Mincha, as they used to say it over BOTH the morning (Shacharit) and afternoon (Mincha) "Tamid" sacrafices? Perhaps the answer is that we DON'T say Shir Shel Yom to remember/mimick the Temple-behavior but for another reasons totally