You might be looking for Nachman bar Huna or Nachman bar Yaakov.
Rav Nachman bar Yitzchak (Hebrew: רב נחמן בר יצחק; died 356 CE) was a Babylonian rabbi, of the fourth and fifth generations of amoraim.
It is generally accepted that references to "Rav Nachman" in the Talmud refer to Rav Nachman bar Yaakov, not to Rav Nachman bar Yitzchak.Tosafot to Gittin 31b takes this position while understanding Rashi as disagreeing. Modern scholarship follows Tosafot, noting that "Rav Nachman" and "Rav Nachman bar Yitzchak" are often stated as disagreeing within a single passage.
Biography
His mother's brother was Rav Aha bar Yosef.Shabbat 140a
Legend states that an astrologer predicted to his mother that her son would become a thief. She required him to have his head covered at all times, though he did not understand the purpose of this requirement. Once he was sitting and studying under a tree, and his head-covering slipped off. He was overcome by desire and took a cluster of dates from the tree (which did not belong to him).Shabbos 156b
He was a disciple of Abaye, Rava, Rav Nachman,Gittin 31a and Rav Chisda.Eruvin 43b In his youth he studied together with Rava, sitting one row behind Rava in the beit midrash and occasionally asking each other questions.Eruvin 43b; Bava Batra 152a
Later on, while Rav Yosef was the head of the yeshivah of Pumbedita, Rava became the head of the yeshivah in Mechoza, while Nachman bar Yitzchak was appointed the chief lecturer (Reish Kallah) under Rava.Bava Batra 22a He later went to Sura, where Rav Nahman bar Chisda drew particular attention to him and frequently repeated his responsa in the beit midrash.Hullin 88b; Shevuot 12b; Ta'anit 21b When Rava died, he succeeded Rava as head of the school (which was transferred from Mahoza to Pumbedita), a position he held for four years.Iggeret Rav Sherira Gaon, 3:3
Teachings Halakha He contributed to halakhah chiefly by collecting, arranging, and transmitting the teachings and decisions of his predecessors, which were thus saved from oblivion. He also employed mnemonics to facilitate memorizing the halakhot which he had arranged,Shabbat 33a, 60b; Taanit 10a; Yabamot 21a; Avodah Zarah 28a; Hullin 106a; Arachin 11a; Niddah 45a thus beginning the redaction of the Talmud. He distinctly recognized his position regarding halakhah, saying of himself "I am neither a sage nor a seer, nor even a scholar as contrasted with the majority. I am a transmitter and a codifier, and the beit ha-midrash follows me in its decisions."Pesachim 105b
He taught that a person who follows Beit Shammai in halacha "deserves death" - in contrast to Rav Yehezkel who says such a person "has acted [i.e., has fulfilled his obligation]", and in accord with Rav Yosef who says such a person "has done nothing."Berakhot 11a
The honor of the Sabbath was of great importance to him. He would personally do menial work in its honor.Shabbat 119a He would say that "one who honors the Sabbath is saved from the oppression of the exile".Shabbat 118b
Aggadah He appears frequently in aggadah as one who arranges and explains the words of other authorities, and he frequently cites Biblical passages in support of their teachings.Arachin 33a When the interpretations by others deviate from the Masoretic vocalization, he attempts to show that reference to the written form of the word in question allows such varying explanations.Yoma 38b, 75b He often interprets rare or ambiguous terms in the Mishnah by citing analogous passages.Beitzah 35b; Yoma 32b
In addition, he also had many independent teachings of his own, including: "Why is wisdom likened to a tree?Proverbs 3:18 Because just as a tiny piece of wood kindles a large one, so the minor Torah scholar sharpens the great scholar."Ta'anit 7a "Whoever enjoys a wedding meal and gladdens the groom, it is as if he built one of the ruins of Jerusalem."Brachot 6b
"Greater is a sin for the sake of Heaven than the fulfillment of a commandment that is not for the sake of heaven".Nazir 23b; Horayot 10b This statement is seen as a justification for the actions of Lot's daughters who had sex with Lot to maintain humanity,Genesis 19 Tamar who pretended to be a prostitute to establish the line of her late husband,Genesis 38 and Yael who (according to the rabbis) had sex with Sisera before killing him.Judges 4-5
He condemned arroganceSotah 5a and anger.Nedarim 22b When Rava stated that a little pride is becoming a scholar, Nachman replied, "Neither it, nor part of it!"Sotah 5a
He had a sense of wit, and often played on the name of a tanna who brought baraitot before him.Berachot 39b, 53b; Gittin 41a He also frequently employed proverbs.Yoma 86a; Shabbat 54a; Sotah 22a
References
It has the following bibliography: Hamburger, R. B. T. ii. 82 et seq.; Bacher, Ag. Bab. Amor. pp. 133-134.