Shemuel fed Rav food to loosen his stuck bowels: Shabbat 108a
Rav cursed him for causing him pain, that he shouldn't have sons: Shabbat 108a
Shemuel and Rav lived by a yard around which all of the residents had merged, to permit transport in the yard on Shabbat. The wall separating their yard from another yard collapsed on Shabbat. Shemuel held there was no need to fix it, but he did so for the sake of privacy. Rav held one couldn't carry the item needed to fix the wall, and he turned his back on the proceedings, but he didn't protest as it was Shemuel's place: Eruvin 94a
Shemuel tore 13 garments when Rav's death was mentioned, saying, "The man I was afraid of is gone.": Moed Katan 24a
Rav cited a law, and said he did not know the reason; "it is a Gemara [tradition]." Shemuel responded, "Abba does not know the reason? This is the reason...": Eruvin 78a
Rav Chiyya bar Yosef asked Shemuel regarding a certain debate, "Does the law follow you, or does it follow Rav?" Shemuel responded that the law follows Rav: Eruvin 90b
Shemuel's approach was followed by people in Neherdaa and its suburbs; Rav's approach was followed by people in Bavel and its suburbs: Ketuvot 54a
Rabbi Elazar quoted a lesson of Rav to Shemuel; Shemuel disapproved forcefully, declaring, "Feed Elazar barley [as in: animal fodder]"! When Rabbi Zeira made aliyah to Israel he heard Rabbi Binyamin bar Yefet quote the lesson in the name of Rabbi Yochanan, and he quoted Shemuel's criticism: Ketuvot 77a
