Midrasz do Królów II 13:14

Until the time of Abraham there was no mark of old age, and anyone who wanted to talk to Abraham spoke to Isaac, or vice versa, [since their appearance was the same]. Then Abraham prayed, and the mark of old age was visible, as it is said (Ib. 47) And Abraham was old. Until the time of Jacob there was no sickness [death occurred suddenly]. Then Jacob prayed that sickness should come before death; as it is said (Ib. 48, 1) Behold, thy father is sick. Until the time of the prophet Elisha there was no one who was cured of sickness. But Elisha prayed and was cured; as it is said (II Kings 13) Elisha was sick of the sickness where he had to die, which signifies that previously he was sick and was cured. Our Rabbis were taught: "Three times was Elisha sick; first at the time he discharged Gechazi from his service, secondly when he set the bears on the children, and the third time when he died."

And thus do you find with Chizkiyahu, king of Judah, who taught all of Torah to Israel and called them "sons," viz. (II Chronicles 29:11) "My sons, now be not lax." And just as disciples are called "sons," so is the master called "father," viz. (II Kings 2:12) "And Elisha saw (Eliyahu being borne aloft) and he cried out 'My father, my father — the chariot of Israel and its riders!'" And he saw him no more, and he took hold of his own garments, etc." And it is written (Ibid. 13:14) "And Elisha fell ill with the illness of which he would die, and Yoash the king of Israel came down to him and wept before him, crying 'My father, my father!'"