סימן ט סעיף כא
הַלּוֹבֵשׁ בֶּגֶד שֶׁהוּא חַיָּב בְּצִיצִית בְּלֹא צִיצִית, הֲרֵי זֶה בִּטֵּל מִצְוַת עֲשֵׂה. וּצְרִיכִין לְהַשְׁגִּיחַ בִּקְצָת בְּגָדִים הָעֲשׂוּיִין בְּאֹפֶן שֶׁיֵּשׁ לָהֶם אַרְבַּע כְּנָפוֹת, צְרִיכִין לַחְתֹּךְ קֶרֶן אֶחָד שֶׁיְּהֵא עָגֹל. אֲבָל אִם כָּפַל אֶת הַקֶּרֶן וּתְפָרוֹ בְּעִנְיָן שֶנִּרְאֶה עָגֹל, לָא מַהֲנֵי, דְּכָל כַּמָּה שֶׁלֹּא חֲתָכוֹ עֲדַיִן, מִכְּלַל הַבֶּגֶד הוּא. וְגָדוֹל עֹנֶשׁ הַמְבַטֵּל מִצְוַת צִיצִית. וְהַזָּהִיר בְּמִצְוַת צִיצִית, זוֹכֶה וְרוֹאֶה פְּנֵי הַשְּׁכִינָה (ח' י' כד).
If a garment that requires tzitzis is worn without tzitzis, this constitutes transgression of a positive command.55See preface to paragraph 20. We must be careful about certain garments that are made with four corners; one corner must be cut so that it becomes rounded.56Leaving the garment with only three “corners” and removing the obligation of tzitzis. However, if the corner was merely folded and sewed it so that it appears round it is not sufficient, because as long as it was not cut, it is still considered part of the garment.57And the garment still has four corners. Note: Only garments that are used to dress the body are obligated to have tzitzis. Therefore, a cloth used as a head-dress does not require tzitzis (Beis Yoseif 10); neither does a scarf (Aruch Hashulchan 3:22). (This would make it doubtful as to whether talleisim worn as scarves, which are available in some synagogues, would constitute a fulfillment of the mitzvah of tzitzis. These talleisim also do not have the required dimensions for a valid tallis.) Great is the punishment for one who negates the mitzvah of tzitzis. One who is scrupulous in this mitzvah will be worthy to behold the Divine Presence.
תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)