גמרא חולין כ"ו::י'
כל מקום שיש תקיעה אין הבדלה וכל מקום שיש הבדלה אין תקיעה.
MISHNA: Any situation where there is a shofar blast sounded on the eve of Shabbos or a Festival to stop the people from performing labor and to demarcate between the sacred and the profane, there is no havdala recited at the conclusion of the Shabbos or Festival in prayer and over a cup of wine. And any situation where there is havdala recited, there is no shofar blast sounded.
יו״ט שחל להיות בע״ש תוקעין ולא מבדילין במ״ש מבדילין ולא תוקעין.
How so? On a Festival that occurs on Shabbos eve, one sounds the shofar to stop the people from performing labor that is permitted on the Festival and prohibited on Shabbos and to demarcate between one sacred day and another; and one does not recite havdala, as that is recited only when the transition is from a sacred day to a profane day or from a day of greater sanctity to a day of lesser sanctity. The sanctity of Shabbos is greater than the sanctity of the Festival, and therefore havdala is not recited in this case. On a Festival that occurs at the conclusion of Shabbos, one recites havdala, but one does not sound the shofar.
According to the simple understanding of the mishna, there is no תקיעת שופר on a regular Motzei Shabbos.
So the Rambam [שבת פ"ה ה"כ] surprises us!!!
תְּקִיעָה רִאשׁוֹנָה תּוֹקֵעַ אוֹתָהּ בְּמִנְחָה. וְהַשְּׁלִישִׁית קָרוֹב לִשְׁקִיעַת הַחַמָּה. וְכֵן תּוֹקְעִין בְּמוֹצָאֵי שַׁבָּת אַחַר צֵאת הַכּוֹכָבִים לְהַתִּיר הָעָם לְמַעֲשֵׂיהֶן:
The first teki'ah should be sounded at [plag] haminchah and the third [teki'ah] close to sunset. Similarly, the shofar should be sounded on Saturday night to [inform] the people that they are permitted [to tend] to their affairs.
Were did THAT come from??
Li-myse - רוח ה' דיבר בו!!!
Incredible!!!!
See Tal Oros P. 69-70....