Plain text of The Gatha Spenta Mainyu · Yasna 20 (Commentary on the Ashem Vohu)
1 A blessing is Righteousness called the best; there is weal, there is weal to this man when the right helps the Righteousness best, when the pious man serves it in truth. God the Wise Lord spake forth: "Righteousness is good, it is the best." To this Righteousness, the holy ritual sanctity, one attributes the qualities of "good" and "best," as one attributes property to an owner; thus this sentence "good, the best, it is" is substantiated at once.
2 "It is happiness, happiness to him": by this attribution of blessedness the praiser assigns every person or thing of a sacred nature to every holy person, and as one usually and regularly assigns everything that is holy to every holy man.
3 "To Righteousness the Best": by these words the worshipper ascribes the entire sacred word to Righteousness the Best, and ascribes all to the sacred word, as one ascribes the kingdom to Righteousness, and as one ascribes righteousness to the invoking saint; yea, as one ascribes righteousness to us who are the prophets who shall help and bless the people. The three maxims of the sentences are thus fulfilled. And every word in its detail, and the entire utterance in its proclamation, is the word of God the Wise Lord.
Catechetical addition
4 The Wise Lord has made a proclamation. Question: Whom did He announce? Answer: That holy one who is both heavenly and earthly. Question: Of what character is He who has thus announced him? Answer: He is the best, and the One who is exercising sovereign power. Question: Of what character is the man whom He announced? Answer: The holy and the best, the one who rules with no capricious tyranny.
We give thanks for the several parts of the prayer of Righteousness the Best. We give thanks for the heard recital of it, its memorising, its chanting, and its sacrificial use!