משנה אויף דברים 4:9

Rabbi Dostai ben Rabbi Yannai said in the name of Rabbi Meir: whoever forgets one word of his study, scripture accounts it to him as if he were mortally guilty, as it is said, “But take utmost care and watch yourselves scrupulously, so that you do not forget the things that you saw with your own eyes” (Deuteronomy 4:9). One could [have inferred that this is the case] even when his study proved [too] hard for him, therefore scripture says, “that they do not fade from your mind as long as you live” (ibid.). Thus, he is not mortally guilty unless he deliberately removes them from his heart.

[If he said]: "I adjure you"; "I command you"; "I bind you"; they are liable. "By heaven and earth!", they are exempt. "By Alef Daleth"; "By Yod He"; "By God Almighty"; "By The Lord of Hosts; "By the Merciful and Gracious one"; "By the Long Suffering One"; "By the One Abounding in Kindness"; or by any of the substitutes [for the name], they are liable. He who blasphemes by any of them is liable, according to the words of Rabbi Meir. And the Sages exempt him. He who curses his father or mother by any of them is liable according to the words of Rabbi Meir. And the Sages exempt him. He who curses himself or his neighbor by any of them transgresses a negative precept. [If he said,] "May God smite you"; or "Yea, may God smite you"; this is the curse written in the Torah. "May [God] not smite you"; or "May he bless you"; Or "May he do good unto you [if you bear testimony for me]": Rabbi Meir makes [them] liable, and the Sages exempt [them].