Berakhot 30B

בנהרדעא, לבר מההוא יומא דאתא פולמוסא דמלכא למתא, ואטרידו רבנן ולא צלו, וצלי לי ביחיד, והואי יחיד שלא בחבר עיר.

in Neharde’a, where there is always a prayer quorum, except for the day when the king’s army [pulmusa] came to the city, and the rabbis were preoccupied and did not pray communally, and I prayed as an individual, and I was an individual who was not praying in a prayer quorum. Shmuel’s conduct was in accordance with the opinion of R' Yehuda in this matter.

יתיב רבי חנינא קרא קמיה דרבי ינאי, ויתיב וקאמר: הלכה כרבי יהודה שאמר משום רבי אלעזר בן עזריה. אמר ליה: פוק קרא קראיך לברא, דאין הלכה כרבי יהודה שאמר משום רבי אלעזר בן עזריה.

Yet this opinion was not universally accepted. The Talmud relates: R' Ḥanina Kara, the Bible expert, sat before R' Yannai, and he sat and he said: The halakha is in accordance with the opinion of R' Yehuda who said it in the name of R' Elazar ben Azarya. R' Yannai said to him: Go and read your verses outside, as that halakha is not accepted by the rabbis in the study hall, and it belongs outside, as the halakha is not in accordance with the opinion of R' Yehuda who said it in the name of R' Elazar ben Azarya.

אמר רבי יוחנן: אני ראיתי את רבי ינאי דצלי והדר צלי. אמר ליה רבי ירמיה לרבי זירא: ודילמא מעיקרא לא כוון דעתיה ולבסוף כוון דעתיה. אמר ליה: חזי מאן גברא רבה דקמסהיד עליה.

R' Yoḥanan said: I saw R' Yannai, who prayed and then prayed again. Presumably, his first prayer was the morning prayer and his second prayer was the additional prayer. Apparently, he does not hold in accordance with the opinion of R' Elazar ben Azarya. Rather, he holds that even when not part of a prayer quorum, an individual must recite the additional prayer. Later on, when this story was related in the study hall, R' Yirmeya said to his teacher, R' Zeira: What proof is there that the second prayer was the additional prayer? Perhaps initially he did not focus his mind on his prayer and ultimately he focused his mind, i.e., he repeated the morning prayer in order to do so with proper concentration. R' Zeira said to him: Look at who the great man is who is testifying about him. R' Yoḥanan certainly observed carefully before relating what he witnessed.