The Levites Harp from Seven Strings to Ten in the World to Come

(Numbers 8:5-6:) "And the LORD spoke etc. Take the Levites." Let our master teach us: how many strings were on the harp upon which the Levites played? Thus did Rabbi Judah teach: there were seven strings on that harp, as it is said (Psalms 16:11), "fullness (sova) of joys is in Your presence" — do not read it sova ("fullness") but sheva ("seven"). And so did David say (Psalms 119:164), "Seven times a day I praise You." And in the days of the Messiah it will be made eight, for so did David say in song (Psalms 6:1), "For the leader, with stringed music, upon the eighth (al ha-sheminit)." And in the time to come it will be made ten, as it is said (Psalms 144:9), "(Sing to God a new song etc.) [O God, a new song I will sing to You; upon a ten-stringed harp (nevel asor) I will make music to You.]" And who established them? Samuel and David, as it is said (1 Chronicles 9:22), "These did David and Samuel the seer establish in their trust." And they set up the divisions of the song, and the Levites would stand upon the platform and sing before the One who spoke and the world came into being. See the affection with which the Holy One, blessed be He, cherished the Levites; and from the beginning the Holy One, blessed be He, ordained concerning them that they should serve Him. Therefore the Holy One, blessed be He, said to Moses: the Levites are exceedingly beloved before Me; take them for My name, for high office, [from where, from what is read in the matter:] "Take the Levites."