The Trisagion and the Trisagion Prayers

Holy God, Holy Mighty, Holy Immortal, have mercy on us. It is sung three times at almost every service and stands at the head of the short sequence of prayers that begins nearly every Orthodox office, so it is the first thing a child learns and the last thing said over a grave. The tradition records it as given during an earthquake at Constantinople in the fifth century, when a child was caught up and heard the angels singing it. It is addressed to the Holy Trinity, not to the Son alone, and that is why the Quinisext Council forbade the addition "who was crucified for us": the phrase is not false of Christ, and attached to this hymn it says the Trinity was crucified.