It is in this watchful spirit that the Byzantine Rite prays at the end of the Liturgy of the Presanctified during Great Lent: "O Master Almighty... Who by Thine ineffable forethought and great goodness hast led us into these hallowed days, for cleansing of souls and bodies, for subduing of passions, and for the hope of resurrection... grant also unto us, O Merciful Lord, to fight the good fight, to finish the course of the Fast, to keep the Faith undivided, to shatter the heads of unseen dragons, to show ourselves victorious over sin, and to come, without condemnation, blamelessly to worship Thy Holy Resurrection."
The little chapters for use at the Hours during Lent are drawn from the prophets Joel and Isaias; they are pertinent extracts from the passages of these seers read for the Epistle on Ash Wednesday (yielding Joel ii, 12-13 and 17), Friday after Ash Wednesday (providing Isaias lviii, 1 and 7), and Tuesday in the first week of Lent (supplying Isaias lv, 6 and 7). Likewise, the antiphons for the Little Hours in Lent are derived thus: Vivo ego (for Prime) comes from Ezechiel xxxiii, 11; while Commendemus and Per arma (for Sext and None) both stem from II Corinthians vi, 4-5 and 7 (that is, from the Epistle of the first Sunday of Lent).
Unfortunately, whilst it sounds Scriptural, I can't locate the source of Advenerunt nobis, the Lenten antiphon for Terce -
(It must be noted that on the Sundays of Lent, the little chapters of the Day Hours and antiphons for the Little Hours are proper, usually drawn from the Epistle and Gospel of the day respectively, just as they are for Septuagesima, Sexagesima and Quinquagesima Sundays.)
The Invitatory anthem for Lent is a reworking of Psalm 126:2 plus phrases redolent of various New Testament passages while not reproducing any: "May it not be vain for you to rise in the morning before the light: For the Lord hath promised a crown to the vigilant." In other words, don't delay arising for Matins - as the Mohammedan muezzin cries, Prayer is better than sleep.
As to the Office hymns appointed, at Matins for Lent the hymn Ex more docti mystico is by St Gregory the Great; at Lauds, O sol salutis intimis (10th century?); and at Vespers, Audi benigne conditor, again by St Gregory.
Each day of Lent having its own proper Mass, at Matins the lessons are homilies on the Gospel of each day - however, on the Sundays, the first two lessons are from Scripture.
A final peculiarity: the Collect used at the Hours is of course that of the Mass of the day, with the important exception that the Collect of weekday Vespers is instead that of the Prayer over the People read at the end of Mass on that day in Lent, after the Postcommunion. It is said that this stems from the old custom that all fasted until after None on Lenten ferias, whereupon Mass was sung followed by Vespers, and only then did the faithful take food. During the middle ages, Mass - and Vespers - began to be said earlier and earlier on fast days, that the faithful could get stuck into their vittles sooner: with the result that the rubrics came to specify that Vespers had to be said before noon during Lent, a rule that endured down to the twentieth century!
(reproduced, with permission from the blog Psallite Sapienter)