פירוש על ברכות 35:6

WITH PHYLACTERIES ON HIS HEAD AND A TORAH SCROLL IN HIS ARM AND READ [FROM IT]. The Braiso says that one may not walk in a cemetery while carrying a sefer Torah and reading from it. Since the reason for this prohibition is because it seems as if we are ridiculing the deceased who can no longer fulfill mitzvos, Tosfos points out that the Braiso is not to be taken literally
And the same ruling applies, that it is prohibited to recite Torah by heart.

There is none so poor as the dead. Cf. fol. 3 b, p. 10 n. 4.