Reference for Megillah 52:9

אמר רבא מריש הוה אמינא האי כורסיא תשמיש דתשמיש הוא ושרי כיון דחזינא דמותבי עלויה ס"ת אמינא תשמיש קדושה הוא ואסור

Rava said: At first I used to think that the stand [on which the Sefer Torah is placed] is an accessory to an accessory and that it is permitted [to throw it away when worn out]. When, however, I saw that the Sefer Torah is placed actually on it, I said that it is an accessory of holiness and is forbidden.

Jastrow