Midrasch zu Bamidbar 10:12

(Fol. 64b) R. Jochanan said in the name of R. Simon b. Jochai: "Wherever you find the words nitzim, or nitzabim [written in the Pentatuch,] it refers to no one but Dathan and Abiram." If so, then how will you explain the passage (Ex. 4, 19) For the men are dead, etc., referring to Dathan and Abiram, and yet on occasions which happened many years later the words nitzim and nitzabim are found mentioned in the Torah? Resh Lakish therefore explained that they became poor." Resh Lakish said: "A man who has no children is accounted as dead, as it is said (Gen. 30, 1) Give me children or else die, and we are taught in a Baraitha that four are accounted as dead: — The pauper, the leper, the blind man, and he who is childless. That a pauper is accounted as dead we derive from the above quoted passage: For the men are dead; the leper, we derive from the following passage (Num. 12, 12) Let her not be as a dead-born child; That a blind one is accounted as dead we derive from this passage (Lam. 3, 6) In dark places hath He set me to dwell, like the dead of olden times; and that one who is childless is accounted as dead we infer from the passage. Give me children or else I die."