Reference for Psalms 44:18

כָּל־זֹ֣את בָּ֭אַתְנוּ וְלֹ֣א שְׁכַחֲנ֑וּךָ וְלֹֽא־שִׁ֝קַּ֗רְנוּ בִּבְרִיתֶֽךָ׃

All this is come upon us; yet have we not forgotten Thee, neither have we been false to Thy covenant.

ספר השרשים