The detail of this story proves a folk rather than a literary source.
The story has three parts. (1) The foolish brother kills his mother in
the bath. (2) The two brothers hide in a tree under which robbers are
dividing their spoil and frighten the robbers away by dropping down a
weight upon them. (3) One robber returns, and gets his tongue cut out.
Compare Zeltner, 62–72; Arcin, 477; Lenz, 51–53; Parsons, Andros
Island, 92–94 and reference note; Sea Islands, 132; Espinosa, JAFL 27:
119–120; Recinos, JAFL 31: 473–474.
(1) See Grimm 147, Old Man Made Young Again, Bolte u. Polívka 3:
193–199, where the killing hot bath is identified with the fire bath
which restores the old to youth, but which either fails when attempted
by a pretender or is employed as a trick to destroy a powerful enemy;
e.g. Ferrand, Madagascar, 67. In Arcin and Zeltner, the story follows
this order: (1) Gold-producing animal, (2) Life-giving staff, (3) Ear
cut off, the life-giving staff taking the place of the killing hot
bath. In a Jamaica version from Richard Morgan, the killing hot bath is
followed by the story of carting the mother about as if she were alive
and extracting hush money from her pretended murderers, as in number
135 (episode G” in Bolte u. Polívka’s analysis of Grimm 61).
(2) and (3) See Grimm 59, Frederick and Catherine; Bolte u. Polívka 1:
520–528.