Hamavdil

16. The brochoh of Hamavdil makes distinctions within four contrasting pairs. The poskim discuss which of them absolutely must be said or heard. Some say one must hear the beginning of the brochoh, the first distinction, i.e., "המבדיל בין קודש לחול," and the end of the brochoh (הגריש"א, ס' מאור השבת ח"ד מכתבי הגרי"י פישר), but it is not crucial to have a phrase similar to the brochoh's ending right before the ending (מ"ב סי' רצ"ו סק"נ). Others say the other three distinctions are also critical (תשו"ת דברי מלכיאל ח"ד סי' ד'). Thus, if one did not hear the entire text of the brochoh, it is best to hear Havdoloh again from someone else if possible.