Śatapatha Brāhmaṇa ("of a hundred paths") 5.5.3

When he has performed the Consecration-ceremony (Abhishekanîya), he does not shave his hair. The reason why he does not shave his hair (is this):--that collected essence of the waters wherewith he is then sprinkled (anointed) is vigour, and it is the hair (of his head) that it reaches first when he is sprinkled; hence were he to shave his hair, he would cause that glory to fall off from him, and would sweep it away: therefore he does not shave his hair.

He does not shave his hair for a year,--religious observance is of equal measure with the year, hence he does not shave for a year: the Kesavapanîya, namely, is a (day of) praise-singing (stoma) with the view of the termination of the religious performance.

Twenty-onefold is (each stotra of) its Morning-service, seventeenfold (of) the Midday-service, fifteen-fold (of) the Evening-service, together with the Uktha (stotras), the Shodasin, and (the twelve stotras of) the Night-service.

The Twilight (hymn) is (performed in the) Trivrit (stoma), and with the Rathantara (tune). For the twenty-onefold (stoma) is he that burns yonder (the sun); from that twenty-onefold one he (the Sacrificer) parts, and descends again to the seventeenfold one; from the seventeenfold one to the fifteenfold one; and from the fifteenfold one he plants his foot on this firm footing, the Trivrit (stoma).

The Rathantara is the Prishtha (stotra) of this (sacrifice); for the Rathantara is this (earth): it is on her, as on a firm footing, he thereby plants his feet. It is an Atirâtra (sacrifice),--the Atirâtra is a firm footing: therefore it is an Atirâtra.

He only cuts down his hair, but does not shave it; for that collected essence of the waters with which he is sprinkled is vigour, and it is the hair that it reaches first when he is sprinkled. Thus were he to shave off his hair he would cause that glory to fall off from him, and would sweep it away. But when he cuts it down, he attaches that glory to his own self: therefore he only cuts down his hair, but does not shave it. This is for him a religious observance: as long as he lives he does not stand on this (earth with bare feet).

From the throne-seat he slips into the shoes; and on shoes (he stands), whatever his vehicle may be, whether a chariot or anything else. For verily he who performs the Râgasûya is high above everything here, and everything here is beneath him;--therefore this is for him a religious observance: as long as he lives he does not stand on the earth (with bare feet).