Musar zu Bamidbar 19:19

זה קרבן אהרן ובניו וגו' ביום המשח אותו . The commandment that the High Priest must offer a daily מנחה offering, part to be offered in the morning and part in the evening, is derived from 6,13: זה קרבן אהרון ביום המשח אותו על מחבת בשמן תעשה. "This is the sacrifice of Aaron…on the day he was anointed….lt shall be prepared with oil on a griddle." This commandment is to ensure that the High Priest prays for the whole community all of whom depend upon him to obtain forgiveness from G–d. The High Priest must concentrate on being the instrument of forgiveness for his people to secure atonement for them and to establish harmony between them and their Maker. In order to be able to secure forgiveness for others, he must first of all secure forgiveness for his own sins. This is why he personally has to bring two such sacrifices daily. We derive this idea from the words והזה הטהור על הטמא, that "only a person who himself is ritually pure can perform the rite of sprinkling blood on the ritually impure" to help him regain ritual purity (Numbers 19,19). The purpose of the קרבן חביתים is to obtain forgiveness for "hidden" sins, sins one is unaware of. The Hebrew word for this is חבוי, hence the sacrifice has to be prepared on a griddle, i.e. מחבת. Thus far Rabbi Menachem HaBavli.