- Question: [Motzei Shabbos 7th Elul 5781]
This Motzei Shabbos is already six days past the Molad, but has yet to reach seven days past the Molad. Now, I know that in general we are careful to wait until the 7th to recite Kiddush Levana, although my question is whether one is to wait until a complete seven days have passed or if it suffices to wait until one has entered the seventh day after passing six full days. Bottom line, should we say Kiddush Levana this Motzei Shabbos, or wait until the next Motzei Shabbos.
You should say it this Motzei Shabbos [or sometime this week if you did not do so] even though it is prior to seven complete days from the Molad, being that six days have already passed
Explanation: It is debated amongst the Poskim regarding if one must wait seven complete days from the Molad, or if it suffices to enter the beginning of the seventh day, and different communities follow different customs. This concept is called Zayin Sheleimim. Practically, Ashkenazim are completely lenient to never wait until seven days have passed, and begin saying it once three days have passed. Sephardim, however, are accustomed to being stringent and wait until a complete seven days have passed from the Molad, and hence they do not say Kiddush Levana on a Motzei Shabbos that is prior to seven complete days. This means that they require Zayin Sheleimim. Regarding the Chabad custom, although we are particular wait until seven days have passed as rule the Sephardim, nonetheless the custom is to be lenient and not wait until the passing of seven complete days, and rather once one has entered the seventh day, then it is to be recited. Thus, one is to have recited Kiddush Levana this past Motzei Shabbos. This is aside from the fact that the Rebbe encouraged saying Kiddush Levana even prior to the seventh day when necessary, and likewise that the Rama rules that one should never wait until Motzei Shabbos that will be past the 10th of the month.
Sources: Poskim who are lenient regarding Zayin Shelimim: Rameh Mepuno 78; Shiyurei Kneses Hagedola; Elya Raba 426:14 [brought in Shaareiy Teshuvah 426:10] that one may say Kiddush Levana on the night of the 7th; Ashel Avraham Butchach 426:2; Poskim who are stringent regarding Zayin Shelimim: Birkeiy Yosef 426:4 brought in Shaareiy Teshuvah 426:10; Mateh Efraim 581:10 rules one is to initially say it only after seven complete days have passed, although if he suspects the moon will not be visible again, he is not to delay the blessing. Regarding the Chabad custom, see: So concludes Hiskashrus 454 p. 15 and so was the custom of Rav Yaakov Landau [as told to me by his son Rav Eliyahu Landa Shlita]. Seemingly the reason one may be lenient is because even regarding waiting seven days there is a dispute and the Rebbe leaves room to be lenient. See also Sichas 1986 6th Adar Rishon that Kiddush Levana was said that Motzei Shabbos even though seven full days had not passed since the Molad.