Since the time immemorial, the threefold motto of “good thoughts, good words and good deeds” has been a fundamental tenet in Zoroastrianism .  This ancient code is acknowledged by Zoroastrians of every shade of doctrinal belief. The motto of “húmata hükhta húvarshta” acts as a unifying factor for the community, and is the basis for far-reaching charity and philanthropy. It simplifies our ancient religion into a very sincere belief in ALL WISE and ALL GOOD GOD, who insists on the purest essence in thoughts, words and deeds, and shapes the faith of the individuals in this world and the next, according to their thoughts, words and deeds. 
In the Haδōkht Nask 2.24-25 the Daäna/inner eyes/insight of a righteous person, is identified with his/her good thoughts, words, and deeds; by which the soul has been made beautiful/shining/brilliant; and (2.33-34) the virtuous ascend through the three stages of “húmata “hükhta húvarshta,” into the eternal lights, and then the celestial house of music & songs of ahúrá mazdá.
 According to the holy Dēnkart Bk. 4 (ed. Madan, p. 413.15-17; tr. Shaki, p. 120:) “the effective power of the religion’s truth lay not so much in exclamation, as in the purest essence in thoughts, words, and deeds, the guidance of the Spirit of Wisdom and worship of the yazatás or the ADORABLE VIRTUES/QUALTIES of an ALL GOOD GOD .”  In Yasht. 13.84 and Yasht. 19.17, the seven great Aməšhá Spəñtás or the “ahuric auspicious immortals” themselves are meditating on “húmata “hükhta húvarshta.”
The earliest occurrence of the formula is at the beginning of Yasna Haptaŋg.hāiti (Yasna. 35.2), Zoroastrian tradition with certainty, and a number of scholars with different levels of convictions, have assigned the composition of Yasna Haptaŋg.hāiti to Prophet Zarathushtra himself (K. Hoffmann apud Barr, p. 285, n. 7; Gershevitch, p. 18; Narten, 1982, p. 137;  1986, pp. 20-37; Boyce, 1992, pp. 87-94;  1995, p. 25; Hintze, pp. 31-33, 45-50); and the prophet can here be seen defining for his followers with simple clarity an ethical formula referred to in more subtle ways in the poetic gathas e.g  first line of Yasna 34.10,  third line of Yasna 45.8 and first line of Yasna 53.2.
“hú or hü,” the first part of the three Avestan words means; “extraction, purest essence, nectar.” It is the same as Sanskrit sú, Old High German saf, german saft, english sap.
“mata” or the second part of the first word of the formula; “to meditate, to think over, consider.” Compare Skt. midiur “I judge, estimate,” Welsh meddwl “mind, thinking,” Gothic. miton, Old.English. metan, Greek. medesthai “think about,” medon “ruler.” In Persian, the Avestan word is translated into “pendaar;” to ponder, to consider, to weigh a matter mentally. 
“ükhta” or the second part of the second word of the formula means;  “utterance,, speech, word.” Compare with Germanr. äussern “to utter, express.” It comes from the root “vac” voice, word, speech, expressed wish/desire.
“varsht” or the second part of the final and third word of the formula occurs frequently in the poetic gathas, and the combination of “húvarsht” appears also in the third line of Yasna 49.4.  The root “varesh/varez means;” “to come to pass, to become.” Compare Germanic wurdiz/wurthis, Old.Slavic. wurd, Old.High.German. wurt, German “werden,” Old.English. weorðan “to become”, from the base “wer-” “to turn, bend.” The ancient NORSE RUNE “WYRD” literally “that which is in the process of happening/becoming;” is identical to the Avestan word and concept here.
The Middle Persian or the Pahlavi renderings of the above three Avestan words are “hu-manishn hu-gōwishn, hu-kunishn.”
A further elucidation of the threefold formula is provided in Yasna 19.19:
kat húmatem, ashavanem mana-paóiryö,
What is the purest essence in thought? The foremost/original in the mind/spirit of the excellent.
kat hükhtem, mánthrö speñtö,
What is the purest essence in utterance/speech? the auspicious, effecive word of the spirit/mantra.
kat húvarshtem, staótáish asha-paóiryáish-cha dámébísh.
What is the purest essence in that which is happening/becoming? The praise/staótá lit.” that which causes to appear/stand, bring into existence;” of the lot/portion (dámébísh from the root dá; to give, allot) who regard “ahuric artistry/virtues” first and above all other things.

In conclusion, i should add that in Mazdyasna or the beautiful religion; the excellence in thoughts, words and deeds is the key to happiness and salvation regardless of one’s religion. Zoroastrianism’s emphasis is and has always been on “virtue and wisdom.” Zoroastrianism teaches us not to care for labels, instead focus on goodness and excellence. As we say in the popular middle persian “hamá zoor” prayer; “may we be of the same force/energy with the virtuous and good, across the seven kingdoms of the earth.”

Ardeshir

Sources: Die Religion des alten Iranier,” German tr. by J. P. Asmussen in Handbuch der Religionsgeschichte, ed. Asmussen and J. Laessoe, vol. II, Göttingen, 1972. M. Boyce, Zoroastrians, Their Religious Beliefs and Practices, London, 1979; 5th corrected repr., 2001.  Zoroastrianism: its Antiquity and Constant Vigour, “Thought, Word and Deed: a Topic of Comparative Religion,” in K. R. Cama Oriental Inst., International Congress Proceedings1989, Bombay, 1991, pp. 41-51. Die Religionen des Alten Iran, German tr. by H. H. Schaeder, Leiden, 1938; repr., Osnabrück, 1966. B. Schlerath, Awesta Wörterbuch, Vorarbeiten II, Wiesbaden, 1968. “Gedanke, Wort und Werk im Veda und im Awesta,” in Antiquitates Indogermanicae, Gedenkschrift H. Güntert, ed. M. Mayrhofer et al., Innsbrücker Beiträge zur Sprachwissenschaft, Bd. 12, 1974, pp. 202-21. M. Shaki, “The Dēnkard Account of the History of the Zoroastrian Scriptures,” Archív Orientální 49, 1981, pp. 114-20. E. W. West, Pahlavi Texts II, SBE 18, Oxford, 1882; repr. Delhi, 1965.