Full text is: Ecce positus est hic in ruinam et in resurrectionem multorum in Israel et in signum cui contradicetur.
Its on the OCO 2015, p 173, on the Office of Readings for the Presentation of the Lord. The source is "ex traditione mediaevali sumpta, in CAO tamen non comparens."
You can find it on page 33 of the Carthusian Vesperale: http://www.chartreux.org/la/scriptum/vesperale_cartusiense.pdf You may also find it in my index to the OCO: http://www.antiphonale.net/IDX.csv This index contains melodies (in gabc format) for most of the OCO antiphons -- with the exception of the day time hours of the Common of Saints. (The csv format is probably not the most appropriate for this kind of data since it has many duplicates, but at least it's easily parseable.)
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