The signature hymn of the early part of Orthodox Holy Week

Behold, the Bridegroom comes at midnight,
and blessed is the servant whom He shall find watching;
and again, unworthy is the servant whom He shall find heedless.
Beware, therefore, O my soul, do not be weighted down with sleep,
lest you be given up to death, and lest you be shut out of the Kingdom!
But rouse yourself, crying: “Holy, holy, holy, are You, O our God!”
Through the Theotokos have mercy on us!

Here’s a link to a PDF of the Hymn Music,