Midrash su Salmi 125:5

Rachaba said in the name of R. Juda who spoke in the name of Rab: "He who sees the [procession of the] dead and does not take part in it transgresses against what is written (Ib.) Whoso mocketh the poor, blasphemeth his Maker." If he does take part what will be his reward? R. Ashi said, "Of such a man, it is said (Ib. 19, 17.) He that hath pity upon the poor lendeth unto the Lord; and also (Ib. 14, 31.) But he that is gracious to the needy honoreth Him" (Fol. 19a) E. Joshua b. Levi said: "He who whispers [with disgraceful intentions] behind the biers of learned men will fall into Gehenna, as it is written (Ps. 125, 5.) But as for those who turn aside into their crooked ways, the Lord shall lead them forth with the workers of wickedness; but peace shall be upon Israel, i.e., even when peace shall be upon Israel, yet shall the Lord lead them forth with the workers of wickedness." Further, said R. Joshua b. Levi: "In twenty-four cases does the court-tribunal excommunicate [a man] for not having paid due respect to the masters of the law [by transgressing their ordinances], and all these cases are mentioned in our Mishnah." R. Elazar asked of him: "Where have they been mentioned?" "Go and find," was the reply. Thereupon R. Elazar went out and sought and found three. "He who whispers behind the biers of learned men; he who disregards the washing of his hands [before meals], and he who behaves haughtily toward Heaven." "He who whispers behind the biers of learned men." What does this mean? It is that which we are taught (in a Mishnah): "He (Akabia b. Mehallalel) also said that a female proselyte and a freed maid-servant are not given the bitter water and the sages say they are. The sages said to him, 'Did this not happen once to a certain Karkmith, a freed maid-slave in Jerusalem, who was made to drink by Shmaya and Abtalion?' He answered them: 'It was for show that they made her drink.' Thereupon the sages placed him under ban, and when he died the court stoned his coffin." Where do we find the reference to one who disregards hand-washing [before meals]? We are taught that R. Juda said: "God forbid [to think] that Akabia b. Mahallalel, who among all Israelites, when the doors of the Temple courtyard were closed, was unequaled in erudition, purity and piety, should have been excommunicated. But to whom then was it done? It was R. Elazar b. Chanoch that was excommunicated for contesting the rule of washing the hands [before the meals], and when he died, the court sent a stone to be put on his coffin; whence we learn that the coffin of him who dies while under ban is to be stoned." And what is he who behaves haughtily towards Heaven? We ere taught that Simon b. Shetaeh sent [word] to Honi the Me'agel: "If thou wert not Honi you should be excommunicated, but what shall I do with thee? since thou art petulant towards God and yet He forgiveth and indulgeth thee like a petted child who is petulant towards his father and is nevertheless forgiven and indulged? To thee may be applied the passage (Pr. 23, 25.) Let (then.) thy father and thy mother rejoice, and let her that hath born thee be glad."