Shulchan Arukh, Orach Chayim Siman 653
Can copy this into an AI, or connect the whole library to your assistant. For deeper learning, you can directly use the original seforim, sites, and apps.
הדס של מצוה אסור להריח בו אבל אתרוג של מצוה מותר להריח בו מן הדין אלא שלפי שנחלקו אם מברכים עליו אם לא יש למנוע מלהריח בו:
It is forbidden to smell the myrtle. Containing 2 paragraphs It is forbidden to smell the myrtle that is used for the mitzvah. Technically, it is permitted to smell the etrog, but because there is a disagreement about whether or not to bless on it, one should refrain from smelling it.
עבד להושענא ולא אגבהה למיפק בה שרי בהנאה:
If [one of the four species] was made for [use as one of the four species] but was not lifted to fulfill an obligation, it is still permissible to get benefit from it.