It was stated: regarding one who derives benefit from the heaped ash that lies upon the altar, Rav said one does not incur the law of trespass against it, and Rabbi Yochanan said one does incur trespass against it. Before the removal of the ashes, all agree there is no dispute. When they dispute, it is after the removal of the ashes. Rav holds one does not incur trespass, for its commandment has already been fulfilled. And Rabbi Yochanan holds that since it is written "and the priest shall put on his linen garment" (Leviticus 6:3), since the priest still requires the priestly garments for the act, the ash remains in its sanctity.
May One Benefit from the Ash Heap upon the Altar
Yalkut Shimoni on Torah 483:4
אִיתְמַר, הַנֶּהֱנֶה מֵאֵפֶר תָּפוּחַ שֶׁעַל גַּבֵּי הַמִּזְבֵּחַ, רַב אֲמַר אֵין מוֹעֲלִין בּוֹ, וְרַבִּי יוֹחָנָן אֲמַר מוֹעֲלִין בּוֹ. לִפְנֵי תְּרוּמַת הַדֶּשֶׁן כֻּלֵּי עָלְמָא לֹא פְּלִיגֵי, כִּי פְּלִיגֵי לְאַחַר תְּרוּמַת הַדֶּשֶׁן, רַב סָבַר, אֵין מוֹעֲלִין, הֲרֵי נַעֲשָׂה מִצְוָתוֹ. וְרַבִּי יוֹחָנָן סָבַר, כֵּיוָן דִּכְתִיב "וְלָבַשׁ הַכֹּהֵן מִדּוֹ בַד", כֵּיוָן דְּצָרִיךְ בִּגְדֵי כְּהֻנָּה, בִּקְדֻשָּׁתֵיהּ קָאֵי.