Beitzah 23A

על גבי חרס ⁠— מותר.

However, placing them on a scalding fragment of earthenware is permitted, as there is no concern of extinguishing or kindling.

ורבה אמר: על גבי חרס נמי אסור, משום דקא מוליד ריחא. רבה ורב יוסף דאמרי תרוייהו: סחופי כסא אשיראי ביומא טבא ⁠— אסור, מאי טעמא ⁠— משום דקמוליד ריחא.

And Rabba said: Placing the spices on a hot piece of earthenware is also prohibited, because it produces a new scent in the earthenware, and one may not create new things on a Festival. The Talmud notes that similarly, Rabba and Rav Yosef both said the following: It is prohibited to overturn a cup containing perfume onto silk garments on a Festival. What is the reason for this prohibition? It is because it produces a new scent in the garment.

ומאי שנא ממוללו ומריח בו וקוטמו ומריח בו? התם ⁠— ריחא מיהא איתא, ואוסופי הוא דקא מוסיף ריחא. הכא ⁠— אולודי הוא דקמוליד ריחא. רבא אמר: על גבי גחלת נמי מותר, מידי דהוה אבשרא אגומרי.

The Talmud asks: And in what way is this case different from the case discussed in the following baraita: One may press a piece of aromatic wood between his fingers and smell it, and one may also snip off a piece of it in order to release its fragrance and smell it? In those cases too he produces a scent. The Talmud answers: There, the scent exists in any case, and he merely adds to the fragrance, as his pressing or snipping causes the smell to be stronger. Here, on the other hand, where he overturns a cup of perfume on clothing, he produces a new scent. Rava, however, said: It is even permitted to sprinkle the aromatic spices on the coals themselves, just as it is permitted to place meat on coals for roasting.

דרש רב גביהא מבי כתיל אפתחא דבי ריש גלותא: קטורא שרי. אמר ליה אמימר: מאי ״קטורא״? אי קטורא בידי ⁠— מעשה אומן הוא, ואי לעשן ⁠— אסור, דהא קא מכבה! אמר ליה רב אשי: לעולם לעשן, מידי דהוה אבשרא אגומרי.

The Talmud relates that Rav Geviha from Bei Katil once taught at the entrance to the house of the Exilarch that ketura is permitted on a Festival; but he did not add any further clarification. Ameimar said to him: What is the meaning of ketura? If it means tying [ketura] ornamental knots by hand, this is the act of a craftsman and is therefore certainly prohibited on a Festival. And if it is referring to burning incense [ketoret], this too is prohibited, as he extinguishes some of the coals when he sprinkles the aromatic powder on them. Rav Ashi said to him: Actually, it is referring to burning incense, which is permitted, just as it is permitted to place meat on coals for roasting.