Reference for Rosh Hashanah 62:16
ורב פפא מאי טעמא לא אמר כרב נחמן בר יצחק אמר לך אי ס"ד רבן יוחנן בן זכאי בימי רבן יוחנן בן זכאי מי הוה לשון של זהורית והתניא כל שנותיו של רבן יוחנן בן זכאי מאה ועשרים שנה מ' שנה עסק בפרקמטיא מ' שנה למד מ' שנה לימד
Why did not R'Papa accept the view of R'Nahman B'Isaac? - He could reply: If you assume It was R'Johanan B'Zaccai [who made the rule], was there in the days of R'Johanan B'Zaccai a thread of scarlet [which turned white]? Has it not been taught: R'Johanan B'Zaccai lived altogether a hundred and twenty years. For forty years he was in business, forty years he studied, and forty years he taught', and it has further been taught: 'For forty years before the destruction of the Temple the thread of scarlet never turned white but it remained red'.<span class="x" onmousemove="('comment',' When then could R Johanan have had an opportunity of making this rule?');"><sup>30</sup></span>