John Lightfoot on Matthew 23:7

[And to be called Rabbi, Rabbi.] I. Concerning the original of this title, see Aruch: "The elder times, which were more worthy, had not need of the title either of Rabban, or Rabbi, or Rabh, to adorn either the wise men of Babylon or the wise men of the land of Israel: for, behold, Hillel comes up out of Babylon, and the title of Rabbi is not added to his name: and thus it was with those who were noble among the prophets; for he saith, Haggai the prophet [not Rabbi Haggai]. Ezra did not come up out of Babylon, &c. [not Rabbi Ezra]; whom they did not honour with the titles of Rabbi when they spoke their names. And we have heard that this had its beginning only in the presidents [of the council] from Rabban Gamaliel the old man, and Rabban Simeon his son, who perished in the destruction of the second Temple: and from Rabban Jochanan Ben Zaccai, who were all presidents. And the title also of Rabbi began from those that were promoted [to be elders] from that time, Rabbi Zadok, and R. Eliezer Ben Jacob: and the thing went forth from the disciples of Rabban Jochanan Ben Zaccai, and onwards. Now the order, as all men use it, is this: Rabbi is greater than Rabh, and Rabban is greater than Rabbi; and he is greater who is called by his own (single) name, than he who is called Rabban."

That this haughty title of Rabbi was not in use before the times of Hillel sufficiently appears from thence, that the doctors before that were called by their plain names, and knew nothing of this title. Antigonus Socheus, Shemaiah and Abtalion, Gebihah Ben Pesisa, Calba Savua, Admon and Hanan, Hillel and Shammai, and many others, whose names we meet with in the Jewish story. Yet you shall find these, that were more ancient, sometimes officiously honoured by the writers of their nation with this title, which they themselves were strangers to. They feign that king Jehoshaphat thus called the learned men: "When he saw (say they) a disciple of the wise men, he rose up out of his throne and embraced him, and kissed him, and called him O Father, Father, Rabbi, Rabbi, Lord, Lord." And Joshua Ben Perachia is called Rabbi Joshua...

II. It was customary, and they loved it, to be saluted with this honourable title, notwithstanding the dissembled axiom among them, Love the work, but hate the title.

1. Disciples were thus taught to salute their masters: "R. Eliezer saith, he that prayeth behind the back of his master, and he that salutes his master,--or returns a salute to his master,--and he that makes himself a separatist from the school of his master,--and he that teaches any thing, which he hath not heard from his master,--he provokes the Divine Majesty to depart from Israel." The Glossers on these words, 'He that salutes, or returns a salute to his master,' thus comment; "he that salutes his master in the same form of words that he salutes other men, and doth not say to him, God save you, Rabbi." It is reported also, that the council excommunicated certain persons four and twenty times, for the honour of master; that is, for not having given due honour to the Rabbins.

2. The masters saluted one another so. "R. Akibah said to R. Eleazar, Rabbi, Rabbi."--"R. Eleazar Ben Simeon, of Magdal Gedor, came from the house of his master, sitting upon an ass: he went forward along the bank of the river rejoicing greatly, and being very much pleased with himself, because he had learned so much of the law. There meets him a very deformed man, and said Save you, Rabbi: he did not salute him again, but on the contrary said thus, 'Raca, how deformed is that man! perhaps all your townsmen are as deformed as you.' He answered, 'I know nothing of that, but go you to the workman that made me, and tell him, how deformed is this vessel which thou hast made!'" &c. And a little after, "when that deformed man was come to his own town, his fellow citizens came out to meet him and said, Save you, O Rabbi, Rabbi, master, master. He [R. Eleazar] saith to them, 'To whom do you say Rabbi, Rabbi?' They answer, 'To him that followeth thee.' He replied, 'If this be a Rabbi, let there not be many such in Israel.'"