Octave Day of All Saints
The custom of celebrating during eight days the feast of All Saints was established by Pope Sixtus IV in 1430 for the universal church.
Justorum animae in manu Dei sunt, et non tanget illos tormentum malitiae: visi sunt oculis insipientium mori: illi autem sunt in pace, alleluia.The souls of the just are in the hand of God, and the torment of malice shall not touch them: in the sight of the unwise they seemed to die, but they are in peace, alleluia.
(Wisdom 3:1-3 from the Offertorium of Mass)
Omnipotens sempiterne Deus, qui nos omnium Sanctorum tuorum merita sub una tribuisti celebritate venerari: quaesumus: ut desideratam nobis tuae propitiationis abundantiam, multiplicatis intercessoribus, largiaris.O Almighty and everlasting God, who hast granted us to honour in one solemn feast the merits of all Thy Saints: we beseech Thee, that, since so many are praying for us, Thou wouldst pour forth upon us the abundance of Thy mercy, for which we long.
The Catholic encyclopaedia on Octaves: http://www.newadvent.org/cathen/11204a.htm