1. The Importance of Rinsing the Mouth Before Morning Blessings

The Rebbe cites the Rebbe Rashab, who teaches that one should not recite the morning blessings—Birchos HaShachar—before rinsing out the mouth in the morning. This practice is rooted in many sources and is considered an important preparation for prayer and blessings upon waking.

2. The Exception of Fast Days

There is an exception to this rule on fast days. Since drinking water is prohibited on a fast day, there is concern that rinsing the mouth might lead to accidentally swallowing water and thus breaking the fast. Therefore, on fast days, we say Birchos HaShachar without first rinsing out the mouth. Some authorities discuss whether mere rinsing, without swallowing, would constitute a violation of the fast, but out of caution, the custom is to forgo rinsing entirely before saying the blessings on such days.

3. How to Properly Rinse According to Halacha

The Rebbe quotes from Sefer Emek HaBrocha regarding how one should rinse: it is not sufficient to rinse just once. Rather, one should rinse two or three times to properly cleanse the mouth before reciting blessings. Additionally, it is recommended that a person cough after rinsing to ensure that any remaining residue or saliva is expelled, further preparing oneself for prayer.