In Chulin 54a it reads: “When Rav Chiyah bar Rav Yosef left (Bavel) [and came to Israel] he met Rabbi Yochanan sitting with Reish Lakish..” Rabbi Yochanan and (his brother-in-law) Reish Lakish are sitting and learning the subject of how to validate if an animal is kosher after it has been slaughtered for eating. Rabbi Chiyah Bar Yosef arrives just recently from Bavel to Israel and interrupts them to bring up a ruling made by Rav who at that time is the leading authority in Bavel.
Reish Lakish immediately complains, “Who is this Rav that we have to accept his opinion?” Commentators suggest two reasons for this statement. One is that Reish Lakish is questioning whether they should take the authority of a Rabbi in Bavel while these scholars live in Israel. The other is that Reish Lakish knows Rav by his real name of Abba and is not familiar with this nickname. Rav is not called by his title until he assumes the leadership of Torah study in Bavel.
Rabbi Yochanan replies that in his youth when both Rav and he attends the daily lectures of Rebbi, Rav sit while he stands.
This insinuation is that Rav is the greater scholar and he is therefore granted permission to sit with the other senior students while Rabbi Yochanan is relegated to standing. Commentators, however, point out that it mentions in Maseches Megillah that all Yeshiva students are already accustomed to sitting while studying Gemara compared to earlier generations as it is now easier to concentrate. It may be a combination of both respect and endurance that Rabbi Yochanan stands.
Reish Lakish then says that he remembers “this good man called Rav”. This seems to substantiate that Reish Lakish’s earlier statement is indeed a case of not realizing that Rav and Abba are the same person and not of mocking his scholarship.
In Chulin 137b it reads: “When Isi Bar Hini left Bavel to come to Israel he met Rabbi Yochanan teaching his son.” Isi Bar Hini leaves Bavel to visit at the Yeshiva in Teveryah. He gets into a discussion with Rabbi Yochanan and mentions that he learns his halacha (Torah Rulings) from Abba Aricha,(Rav). Rav’s real name is Abba, but out of respect he is called Rav, or master. He is also called Aricha (Long One) affectionately for two reasons- one is that he is relatively taller than others at his Yeshiva as well as meaning the ‘Imposing One’, due to his superior intellect.
Rabbi Yochanan admonishes Bar Hini that even if he is on a first name basis with the Rosh Yeshiva where he studies in Bavel, Isi is still obligated to give him respect and refer to him as Rav publicly. He punctuates his point by saying: “When I was a student learning under Rebbi here in Israel, Rav was permitted to engage in conversation with him. I sat seventeen rows back and could not readily understand their discussion.”
Finally, on Chulin 84a, Rabbi Yochanan does refer to Rav as Abba when bringing up examples of how healthy people budget their food intake for the week.