Reference for Shabbat 229:1
מותר בקניבת ירק (ואמר רבי חייא בר אבא אמר רבי יוחנן יום כיפורים שחל להיות בחול) מפצעין באגוזים ומפרכסין ברימונים מן המנחה ולמעלה מפני עגמת נפש דבי רב יהודה מקנבי כרבא דבי רבה גרדי קארי כיון דחזא דהוו קא מחרפי אמר להו אתא איגרתא ממערבא משמיה דר' יוחנן דאסיר:
the trimming of vegetables is permitted. Nuts may be cracked and pomegranates scraped from the [time of] minhah and onwards, on account of one's vexation.<span class="x" onmousemove="('comment',' Lit., 'grief of the soul'. It would be very vexing if the breaking of the Fast had to be delayed whilst these are prepared (Baal Ha-Ma'or V. Marginal Gloss.; Rashi explains it differently) ');"><sup>1</sup></span> The household of Rab Judah trimmed cabbage. Rabbah's household scraped pumpkins. Seeing that they were doing this [too] early,<span class="x" onmousemove="('comment',' Before the time of minhah. ');"><sup>2</sup></span> he said to them, A letter has come from the west in R. Johanan's name [to the elect] that this is forbidden.<span class="x" onmousemove="('comment',' Such letters afford examples of early Rabbinic Responsa. ');"><sup>3</sup></span>