Reference for Rosh Hashanah 56:25
אמר ליה ר' זירא לשמעיה
Raba says: For the performance of his religious duty, he does not require to put his mind to it. For transgression [by adding to the precept], he does require to put his mind. But what of the sprinkling of blood, where, according to R'Joshua, he transgresses though he does not put his mind to it?<span class="x" onmousemove="('comment',' He does not intend to sprinkle the blood of the firstborn in the last three installments.');"><sup>26</sup></span> Raba therefore [corrected himself and] said: For the performance of the religious duty he does not require to put his mind to it; for [being accounted to have committed a] transgression [by adding to the precept] if [the act is done] in proper time, he does not require to put his mind to it; if it is not done in its proper time he does require to put his mind to it. R'Zera said to his attendant: