This mitzvah of tzitzit is the equivalent of all the mitzvot combined. -- Talmud Menachot 43b.
Whoever observes the mitzvah of tzitzit meticulously will be found worthy of beholding the Divine Presence. -- ibid.
Rabbi Eliezer ben Yaakov said: He who has tefillin on his head and arm, tzitzit fringes on his garment, and a mezuzah on his doorway, presumably will not sin. As it is stated (Ecclesiastes 4:12), "a three-stranded cord will not quickly be broken." -- ibid.
Rabbi Nattan said: there is no "minor" mitzvah in the Torah whose observance isn't rewarded in this world and the next. How much is the reward? Let us use the mitzvah of tzitzit as an example:
There was once a man who was meticulous in the observance of the mitzvah of tzitzit. He heard that there was a harlot in a faraway city who charged four hundred gold talents for her services. He sent her the exorbitant fee and set an appointed time to meet her. When he arrived at the appointed time ... she prepared for him seven beds, one atop the other -- six of silver and the highest one was made of gold. Six silver ladders led to the six silver beds, and a golden ladder led to the uppermost one. The prostitute unclothed herself and sat on the uppermost bed, and he, too, joined her. As he was unclothing himself, the four fringes of his tzitzit slapped him in his face. He immediately slid off the bed on to the floor, where he was quickly joined by the woman.
"I swear by the Roman Caesar," the harlot exclaimed, "I will not leave you until you reveal to me what flaw you have found in me!"
"I swear," the Jew replied, "that I have never seen a woman as beautiful as you. However, there is one mitzvah which we were commanded by our G‑d, and tzitzit is its name. Concerning this mitzvah it is twice stated in the Torah 'I am the L-rd your G‑d' -- 'I am the one who will seek retribution, and I am the one who will reward.' Now the four tzitzit appeared to me as four witnesses, testifying to this truth."
"I still will not leave you," the prostitute said, "until you provide me with your name, the names of your city, rabbi and the school in which you study Torah."
He wrote down all the information and handed it to her.
The woman sold all her possessions. A third of the money she gave to the government (as a payoff so that they would allow her to convert to Judaism), a third she handed out to the poor, and the remaining third she took with her -- along with the silver and gold beds -- and she proceeded to the school which the man had named, the study hall of Rabbi Chiya.
"Rabbi," she said to Rabbi Chiya, "I would like to convert to Judaism."
"Perhaps," Rabbi Chiya responded, "you desire to convert because you have taken a liking to a Jewish man?"
The woman pulled out the piece of paper with the information and related to the rabbi the miracle which transpired with the tzitzit.
"You may go and claim that which is rightfully yours [i.e. the right to convert]," the rabbi proclaimed.
She ended up marrying the man. Those very beds which she originally prepared for him illicitly, she now prepared for him lawfully. Such was his reward for meticulously observing the mitzvah of tzitzit.
And the reward in the World-to-Come? That we cannot even fathom!
-- Talmud Menachot 44a.
One who meticulously observes the mitzvah of tzitzit is rewarded with [the resources to afford] a nice wardrobe. -- Talmud Shabbat 23b.
"This is my G‑d and I will beautify Him" (Exodus 15:2). Be beautiful before him with mitzvot ... a beautiful tallit. -- Talmud Shabbat 133b.
A Torah scholar must be proficient in the laws of tzitzit. -- Talmud Chulin 9a.
G‑d told Abraham: "You told the king of Sodom, 'Neither from a thread to a shoe strap, nor will I take from whatever is yours' (Genesis 14:23). I swear that as a reward I will give your children the mitzvah of the tzitzit thread." -- Midrash Rabbah Genesis 43:13.
"The L-rd desires for the sake of Israel's righteousness to make the Torah great and glorious" (Isaiah 42:21). G‑d did not leave anything in His world which does not involve a mitzvah for Israel. Humans wear clothing, so G‑d commanded to attach tzitzit to their garments. -- Midrash Rabbah Numbers 17:7.
Whoever observes the mitzvah of tzitzit, regarding him it is said (Zechariah 8:23): "In those days, when ten men of all the languages of the nations shall take hold of the corners of the garment of a Jewish man, saying, 'Let us go with you, for we have heard that G‑d is with you.'" -- Sifri Numbers 115.
The numerical value of the word tzitzit is 600, with eight strings and five knots -- this equals 613, the amount of the commandments of the Torah. -- Pesikta Zutreta Shelach.
Whoever observes the mitzvah of tzitzit, it is considered as if he has observed the entire Torah. -- ibid.
Said Rabbi Shimon bar Yochai: When a person rises in the morning and dons the tefillin and tzitzit ... the Divine Presence dwells upon this person and proclaims: "You are My servant, Israel, in whom I will be glorified!" -- Zohar Chadash, Terumah 41d.
With the tzitzit, as with the brass snake, "every one that is bitten, when he sees it he shall live." -- Zohar III 175a.