Pahlavi Texts, Part III (SBE24), E.W. West, tr. [1885], at sacred-texts.com
1. The ninety-sixth subject is this, when any one departs to that other world it is not proper for others that they should utter an outcry, maintain grief, and make lamentation and weeping. 2. Because every tear that issues from the eyes becomes one drop of that river 5 before the Kinvad
bridge, and then the soul of that dead person remains at that place; it is difficult for it to make a passage there, and it is not able to pass over the Kinvad bridge. 3. It is therefore necessary that they recite the Avesta and celebrate the ceremonial, so that the passage of that place may become easy for it.
358:5 'This river is the many tears that men shed from their eyes, as they make lamentation and weeping for the departed. They shed those tears unlawfully, and they swell to this river. Those who are not able to cross over are those for whom, after their departure, p. 359 much lamentation and weeping were made; and those who cross more easily are those for whom less was made' (AV. XVI, 7-10).