Reference for Psalms 71:9

אַֽל־תַּ֭שְׁלִיכֵנִי לְעֵ֣ת זִקְנָ֑ה כִּכְל֥וֹת כֹּ֝חִ֗י אַֽל־תַּעַזְבֵֽנִי׃

Cast me not off in the time of old age; When my strength faileth, forsake me not.