Shemirat HaLashon שמירת הלשון

I have come, further, to awaken ourselves to [the significance of] something we say every day in the section of tzitzith (Bamidbar 15:39): "And you shall see it, and you shall remember all the mitzvoth of the L-rd." Our Rabbis of blessed memory have said concerning this (Menachoth 43b): "Seeing leads to remembering and remembering leads to doing." But when is this of avail? When he studies and knows the mitzvoth but is afraid that he might forget them. Tzitzith avails for this, that he will remember them and not forget them, and, as a matter of course, he will come to fulfill them. But if he does not know the mitzvoth, how will tzitzith avail him? Therefore, it is very desirable that one learn all of the book, Mitzvoth Hashem, or, at least, Kitzur Sefer Charedim which is included in Zichru Torath Mosheh of the Chayeh Adam. He will thereby know the mitzvoth and will fulfill correctly the mitzvah of tzitzith.

Now, in truth, tzitzith is comparable to a list that a man makes when he travels to buy merchandise and which he refers to several times so as to fix in his mind which merchandise to buy. But all this is of avail only when he knows and recognizes the types of merchandise. However, if he does not, then even if he looks at the list the whole day, he will not know what to buy. Therefore, it is well to do as we have written.

And the verse implies that the seeing of the tzitzith is of avail in spurring one [to do] the mitzvoth of the L-rd and not to go astray after his eyes. If so, how fitting it is to look at them several times a day, especially when some impure thought or some [kind of] anger enters his heart. It is then highly advisable to gaze upon the tzitzith, whereupon the yetzer will depart.