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.
Rashi on Psalms
at the time of old age If I have aged with sins, meaning, I have sinned exceedingly.