On Friday night it is customary to say, “Vayichulu Hashamayim Vihaaretz” both in shul as well as over a cup of wine. The question is however, why is this paragraph in specific so essential to Shabbos that it has to be said so many times?
The purpose of saying these specific psukim preceding the actually bracha on the wine is because these verses are testimony that Hakadosh Baruch Hu created the world in six days and that he rested on the seventh.
The Zohar on Parshas Vayakhel even goes so far as to say that one, who says these words, has atoned for his sins. It is written in the Or Zaruah, that one says it three times because the word “asher” is written three times in the passage. This “asher” is corresponding to the passage of Parah Aduma which also has the word “asher” written three times. We therefore derive from here that anyone who says “Vayichula” three times will be atoned from all of their sins.
It is written in the Gemara (Shabbos 119b) however, that one who says, “Vayichulu…” has not necessarily atoned for his sins but he has in fact acted as a partner with Hakadosh Baruch Hu in the creation of the world.
It can therefore be seen that saying Vayichulu on Friday night is an extra special prayer that is essential in the observance of Shabbos. It is therefore understandable as to why an emphasis is placed on saying it.