Euphemia the Great Martyr
In 451, during the reign of the Sovereigns Marcian and Pulcheria, the Fourth Ecumenical Council was convoked in Chalcedon against Eutyches and those of like mind with him. After much debate, the Fathers who were the defenders of Orthodoxy, being 630 in number, agreed among themselves and with those who were of contrary mind, to write their respective definitions of faith in separate books, and to ask God to confirm the truth in this matter. When they had prepared these texts, they placed the two tomes in the case that held Saint Euphemia's relics, sealed it, and departed. After three days of night-long supplications, they opened the reliquary in the presence of the Emperor, and found the tome of the heretics under the feet of the Martyr, and that of the Orthodox in her right hand. (For her life, see Sept. 16.)
Apolytikion in the Third Tone
O Euphemia, Christ's comely virgin, thou didst fill the Orthodox with gladness and didst cover with shame all the heretics; for at the holy Fourth Council in Chalcedon, thou didst confirm what the Fathers decreed aright. O all-glorious Great Martyr, do thou entreat Christ God that His great mercy may be granted unto us.
Kontakion in the Second Tone
You made fervent effort in your struggles of trial, in your struggles of faith for Christ your bridegroom. But even now, intercede with the Theotokos that the heresies and insolence of enemies be trod beneath the feet of our rulers, O All Praised, who received and kept the Decree of the 630 God-bearing Fathers.