על החוקים לפרטיהם, ספר א נ׳On the Special Laws, Book I 50

א׳
1[267] I must now also fulfil my promise to describe the special qualities of these ashes. They are not merely the ashes of wood consumed by fire but also of a living creature well-suited to a rite of purification such as this.
ב׳
2[268] He orders a red heifer which has never been yoked and without blemish to be taken outside the city and there slaughtered. Then the high priest is to take of the blood and sprinkle it seven times over everything in front of the sanctuary, then burn it wholly to ashes with the skin and flesh and blood and the belly filled with its ordure. When the flame is dying down, he is to cast right into the middle these three things, cedar wood and hyssop and scarlet wool. Then if it is quite extinguished, a clean man is to collect the ashes and deposit them outside the city in a clean place. 
ג׳
3[269] What these things symbolically indicate has been described in full elsewhere where we have expounded the allegory.  So we see that they who mean to resort to the temple to take part in sacrifice must needs have their bodies made clean and bright,  and before their bodies their souls. For the soul is queen and mistress, superior to the body in every way because a diviner nature has been allotted to it. The mind is cleansed by wisdom and the truths of wisdom’s teaching which guide its steps to the contemplation of the universe and all that is therein, and by the sacred company of the other virtues and by the practice of them shewn in noble and highly praiseworthy actions.
ד׳
4[270] He, then, who is adorned with these may come with boldness to the sanctuary as his true home, the best of all mansions, there to present himself as victim. But anyone whose heart is the seat of lurking covetousness and wrongful cravings should remain still and hide his face in confusion and curb the shameless madness which would rashly venture where caution is profitable. For the holy place of the truly Existent is closed ground to the unholy.
ה׳
5[271] To such a one I would say, “Good sir, God does not rejoice in sacrifices even if one offer hecatombs, for all things are His possessions, yet though He possesses  He needs none of them, but He rejoices in the will to love Him and in men that practise holiness, and from these He accepts plain meal or barley,  and things of least price, holding them most precious rather than those of highest cost.”
ו׳
6[272] And indeed though the worshippers bring nothing else, in bringing themselves they offer the best of sacrifices, the full and truly perfect oblation of noble living,  as they honour with hymns and thanksgivings their Benefactor and Saviour, God, sometimes with the organs of speech, sometimes without tongue or lips, when within the soul alone their minds recite the tale or utter the cry of praise. These one ear only can apprehend, the ear of God, for human hearing cannot reach to the perception of such.