Ecclesiastical History VII.5 — Nicene and Post-Nicene Fathers, series 2, vol. 2 (Chester D. Hartranft, 1890) (public domain)
Soon after the enactment of this law, Theodosius went to Constantinople. The Arians, under the guidance of Demophilus, still retained possession of the churches. Gregory of Nazianzen presided over those who maintain the “consubstantiality” of the Holy Trinity, and assembled them together in a little dwelling, which had been altered into the form of a house of prayer, by those who held the same opinions and had a like form of worship. It subsequently became one of the most conspicuous in the city, and is so now, not only for the beauty and number of its structures, but also for the advantages accruing to it from the visible manifestations of God. For the power of God was there manifested, and was helpful both in waking visions and in dreams, often for the relief of many diseases and for those afflicted by some sudden transmutation in their affairs. The power was accredited to Mary, the Mother of God, the holy virgin, for she does manifest herself in this way. The name of Anastasia was given to this church, because, as I believe, the Nicene doctrines which were fallen into disuse in Constantinople, and, so to speak, buried by reason of the power of the heterodox, arose from the dead and were again quickened through the discourses of Gregory; or, as I have heard, some affirm with assurance that one day, when the people were met together for worship in this edifice, a pregnant woman fell from the highest gallery, and was found dead on the spot; but that, at the prayer of the whole congregation, she was restored to life, and she and the infant were saved. On account of the occurrence of this divine marvel, the place, as some assert, obtained its name.
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 2, vol. 2 (Chester D. Hartranft, 1890) (Public domain).
Why Pitre cites it
At a church in Constantinople 'the power of God' healed many diseases, and 'the power was accredited to Mary, the Mother of God.' A fifth-century record of Marian intercession.
Notes
First paragraph of VII.5 (the Anastasia passage): 'The power was accredited to Mary, the Mother of God, the holy virgin, for she does manifest herself in this way.' The chapter's second paragraph (Demophilus' expulsion) omitted.