Barring my faulty memory, and if I’m not lazy, I want to post prayers on Monday from all over Church History and then throughout the modern day, and then my own. This one comes from Hilary of Poitiers.
Keep this piety of my faith undefiled, I beseech you, and let this be the utterance of my convictions even to the last breath of my spirit: that I may always hold fast to that which I profess in the creed of my regeneration when I was baptized in the Father, Son and Holy Spirit, namely, that I may adore you, our Father, and your Son together with you, and that I may gain the favor of your Holy Spirit who is from you through the only-begotten. He is a suitable witness for my faith who says: ‘Father, all things that are mine are thine, and thine are mine,’ my Lord Jesus Christ, who always abides as God in you, from you and with you who is blessed forever and ever. Amen