Halakha Amsal 17:5: Mishneh Torah, Reading the Shema, Mishneh Torah, Tefillin, Mezuzah and the Torah Scroll, Shulchan Arukh, Yoreh De'ah & Sefer HaChinukh

The Shema is not to be read in a bath house nor in a latrine, even if there is no ordure in it, nor in a graveyard, nor in proximity to a corpse. One is permitted to read it after moving away from the grave of a corpse to a distance of at least four cubits. If the Shema was read in a place where it was improper to do so, it must be read a second time.

A person should not walk in a cemetery with phylacteries on his head. When he is within a distance of four cubits from a corpse or a grave, the phylacteries are to be removed till he has passed on to a distance outside four cubits. Phylacteries must not be put on before one is decently covered and has put on his garments. If a person is carrying a burden on his head, he must remove the phylactery from his head, and may not put it on till he has removed the burden. Even a kerchief [alone] may not be put upon the head when one is wearing phylacteries. But he puts his cap over the phylactery.

One who sees a corpse and does not escort him transgresses thereby, 'Whoso mocketh the poor¹²e., the dead. [blasphemeth his Maker],¹³Prov. XVII, 5. This ruling is found in Ber. 18a. Cf. Derek Ereẓ Zuta § and should be placed under a ban;¹⁴M.K. ibid. supra § 343 and notes. and one should escort him at least four cubits.¹⁵R. Jonah and Asheri to Ber. ibid. This applies only if there are sufficient people present at the funeral escort. Otherwise, one must escort the corpse to the grave.