Because of the lofty idea that the moon’s renewal represents, Birkat Ha-levana has been hallowed to the point that one who recites it is viewed as if he is greeting the Shekhina (Divine Presence). Thus, in the academy of Rabbi Yishmael it was taught: “Were the people of Israel privileged to greet the presence of their heavenly Father only once a month (when reciting Birkat Ha-levana), it would have been sufficient for them” (San. 42a). Therefore, Abaye concluded that one must honor the berakha and recite it while standing (San. 42a.). One who finds it difficult to stand should lean on his cane or a friend and recite the berakha. And if leaning is too difficult, he may recite it while sitting.
It is customary to honor the berakha by reciting it with a minyan. In the absence of a minyan, it is best to recite it in a group of three, but technically one may recite it alone. If one is concerned that if he puts off reciting the berakha until a minyan can be gathered he will forget to recite the berakha altogether, it is preferable not to wait, but to recite it alone (bhl 426:2, s.v. “ela”).
It is customary to go outside and recite the berakha under the open sky. After all, we learned above that Birkat Ha-levana is compared to greeting the Shekhina. Therefore, one should approach reciting this berakha as if one is going out to greet a king. One who is sick or concerned that he might catch a cold if he ventures outside may view the moon through a window and recite the berakha indoors (mb 426:21).
In order to honor the berakha, which entails an aspect of greeting the Shekhina, we are accustomed to reciting it immediately after Shabbat, when we are joyful and dressed nicely. However, if there is reason to be concerned that waiting until Motza’ei Shabbat will cause us to miss the opportunity to recite the berakha altogether, it is preferable to recite it on a weeknight (sa, Rema 426:2).
It is customary not to recite Birkat Ha-levana on Friday night, in order to avoid mingling the joy of Shabbat with that of Birkat Ha-levana. However, if there is reason to be concerned that one might not recite the berakha on time, he should recite it on Friday night (Rema 426:2, mb 426:12).
As we already learned, the moon alludes to Knesset Yisrael (the Assembly of Israel). Like a bride before God, Knesset Yisrael renews and purifies itself every month, just as a bride does for her husband. This strengthens the bond between Knesset Yisrael and God. And when all of the world’s flaws are remedied, everyone will recognize the special relationship that exists between Israel and God, as it says, “As a bridegroom rejoices over his bride, so will your God rejoice over you” (Yeshayahu 62:5). Therefore, a custom developed to dance and sing after Birkat Ha-levana. Along the same lines, there is a custom to rise on one’s toes slightly when saying, “Just as I leap toward You…” (Rema 426:2).
Since we must recite the berakha joyously, we do not recite it before Tisha Be-Av, when we are mourning the Temple’s destruction, or before Yom Kippur, due to the anxiety of the upcoming Day of Judgment. We do recite it, however, immediately after Yom Kippur, even though we have not yet eaten, because we are overjoyed to have had the privilege to stand before God in penitence. It is proper to postpone Kiddush Levana until the night after Tisha Be-Av, or until people have had a chance to eat and drink and leave their state of mourning (Rema 426:2). However, if it will be difficult to gather a minyan later on, a congregation may recite Birkat Ha-levana immediately after the fast is over (mb 426:11, sht 426:9; see also below 10:19).
Similarly, one who is sitting shiva should postpone reciting Birkat Ha-levana until after the shiva period is over, if possible, even if he will have to recite it alone, because he is grieving. If, however, he cannot postpone it, because shiva will end after the permissible time to recite the berakha, he should recite it even during his mourning period (mb 426:11, Kaf Ha-ĥayim 426:5; the latest time to recite the berakha will be elucidated below, section 18).