Rashi on Numbers 10:36/רש"י על במדבר י׳:ל״ו

1‘שובה ה [AND WHEN IT RESTED HE SAID] שובה O LORD — Menachem ben Seruk renders it (the word שובה) by an expression denoting “rest”. Similar is (Isaiah 30:15) “In rest (בשובה) and tranquility shall ye be saved” (cf. Ibn. Ezra).

2רבבות אלפי ישראל [GIVE REST O LORD UNTO] THE MYRIADS OF THOUSANDS OF ISRAEL — This teaches us that the Shechinah does not rest upon Israel if they are less in number than twenty-two thousand (Yevamot 64a; Sifrei Bamidbar 84:5).