Sexagesima (sixtieth) means “six times ten”, and thus, by six are understood the works of mercy, and by ten, the Decalogue... and just as the Lord, after working for six days, blessed the seventh, so after perfecting the works of the Decalogue, we will come to eternal blessedness, and He will say to us, “Come, ye blessed.” (Matthew 25, 31-46, the Gospel of the first Monday of Lent.)
Icon of the The Last Judgment, 1640-41, by Franghias Kavertzas. In the Byzantine Rite, today is known as both Meatfare Sunday, from the custom that it is the last day on which meat may be eaten before the fast of Great Lent begins, or the Sunday of the Last Judgment, from the Gospel read at the Divine Liturgy. (Public domainimage from Wikimedia Commons.)
And therefore, on Sexagesima is read the Gospel, “When a very great multitude (was gathered together; Luke 8, 4-15)”, about the seed of the word of God, so that men may sow the works of mercy, in order to have that blessing. And because in most that seed is suffocated, therefore (the Church) cries out in the Introit, “Arise, why does thou sleep, o Lord?” But on the third Sunday (of Forelent), namely, on Quinquagesima, she shows by Whom she wishes to be freed, namely, by God, whence she says in the Introit, “Be thou unto me God and protector”; and because the Lord is near to all who call upon Him, that liberation follows on the next Sunday, whience she says in the Introit, “He will call upon me, and I will hear him.” For it is impossible that he not be freed, who through confession lays bare his sins, which are the griefs that lead to hell (mentioned in the Introit of Septuagesima), and grieves with a grief that makes satisfaction (for his sins), and asks to be free by the Lord. But, because sins separate a man from God, therefore in doubt he cries out (William Durandus, De Div. Off. VI, 26, 2-3)
Arise, why dost Thou sleep, o Lord? Arise, and drive us not away forever; why dost Thou turn Thy face away, forgetting our tribulation? Our belly cleaveth to the earth; arise, O Lord, help us, and deliver us. Ps. 43 O God, our ears have heard, our fathers have declared to us. Glory be. As it was. Arise. (The Introit of Sexagesima Sunday.)
Exsurge, quare obdormis, Dómine? exsurge, et ne repellas in finem: quare faciem tuam avertis, oblivísceris tribulatiónem nostram? adháesit in terra venter noster: exsurge, Dómine, ádjuva nos, et líbera nos. Ps. 43 Deus, áuribus nostris audívimus: patres nostri annuntiavérunt nobis. Gloria Patri. Sicut erat. Exsurge.