שֵׁ֣שֶׁת יָמִים֮ יֵעָשֶׂ֣ה מְלָאכָה֒ וּבַיּ֣וֹם הַשְּׁבִיעִ֗י שַׁבַּ֧ת שַׁבָּת֛וֹן קֹ֖דֶשׁ לַיהוָ֑ה כָּל־הָעֹשֶׂ֧ה מְלָאכָ֛ה בְּי֥וֹם הַשַּׁבָּ֖ת מ֥וֹת יוּמָֽת׃
Six days shall work be done; but on the seventh day is a sabbath of solemn rest, holy to the LORD; whosoever doeth any work in the sabbath day, he shall surely be put to death.
Siddur Sefard
After the Shemoneh Esrei has been said, the entire congregation repeats וַיְכֻלּוּ , in testimony of our belief that God created heaven and earth. According to Halacha, when one is a witness, he must stand and declare his testimony aloud.