Commentary for Rosh Hashanah 56:20

[ממאי] דלמא קסבר ר' יהושע מצות עובר עליהן אפי' שלא בזמנן

To which R'Joshua replied: The precept 'thou shalt not diminish' applies only where the act is withheld from the same subject.<span class="x" onmousemove="('comment',' Lit., 'when it (the instrument of the religious act) is by itself'.');">²⁰</span> R'Joshua said further to him: If you do not sprinkle [four times], you transgress the rule of 'thou shalt not diminish', but you do not perform any positive action,<span class="x" onmousemove="('comment',' I.e., the sin is one of omission only.');">²¹</span>

Rashi on Rosh Hashanah