Mishnah Berurah — משנה ברורה

It is not a commandment on the person - With this he answers why women make a blessing on a lulav which is also a positive commandment which is time-dependent; and he answers that it's different over there (ie. by ציצית) because it's not an obligation on the person. For even a man does not have a Torah level obligation to buy a four cornered garment; rather, if he is does wrap[in a four cornered garment], he is obligated to make ציצית for it. As opposed to [the מצוה of] lulav - that for a person it is an obligation on the person which is a obligation on the body. And you should know, that we rule regarding ציצית, that it is an obligation on the person and it is not an obligation on the person, and both [cases] we rule leniently. [When we say it's an] obligation on the person [and it's ruled] leniently - it's to exclude an obligation on the item (ie. the garment); for as long as he's not wearing the garment, even though it has 4 corners, it is exempt from ציצית. [And when we say it's] not an obligation on the person [and it's ruled] leniently - [it means] that he's not obligated to buy himself a [4 cornered] garment in order to obligate it in ציצית; just that if he has a garment with 4 corners and he wears it, then it's obligated in ציצית. See further in siman 19.