V'Sham'ru is a prayer sung every Friday evening at Shabbat services. It comes from Exodus 31:16-17, regarding the order to keep Shabbat as a rest, just as G-d promises a time of rest and peace for all people.
Hebrew:
V’shamru v’nei Yisrael et ha-Shabbat,
La’asot et ha-Shabbat l’dorotam, b’rit olam.
Bei-ni u-vein b’nei Yisrael ot hi l’olam.
Ki shei-shet ya-mim ah-sah Adonai,
Et ha-sha-mayim v’et ha’aretz,
uva-yom hashvi’i shavat va-yi-nafash.
English Translation:
The people of Israel shall keep the Sabbath,
observing it in every generation as a covenant for all time.
It is a sign forever between me and the people of Israel,
for in six days the Eternal God made heaven and earth,
and on the seventh day God rested and was refreshed.