Green’s Dictionary of Slang

a general excl. oath; by God!

1700		Farquhar Constant Couple II iv: Ecod, I make a very handsome woman, ecod, I do!
1721		Penkethman’s Jests 13: Ecod, when the Spaniard meddled with Q. Elizabeth, he took the wrong SOW by the Ear.
1733		Fielding Don Quixote I viii: ’Ecod! it runs in my Head that he is come to stand for Parliament.
1741		‘Conny Keyber’ Apology for the Life of Mrs. Shamela Andrews 17: I’cod, now it comes into my Head.
1751		Smollett Peregrine Pickle (1964) 604: Ah! pize upon it! Dick, after all, was the man. Ecod! he rounded it off.
1764		Foote Mayor of Garrat in Works (1799) I 178: Ecod, George Gage, the exciseman, is nothing at all to un.
1773		O. Goldsmith She Stoops to Conquer Act I: Ecod, if you mind him, he’ll persuade you that his mother was an alderman, and his aunt a justice of peace.
1776		Foote A Trip to Calais in Works (1799) II 346: If none of her complishes were more handsome than she, ecod they might open their doors without any great danger.
1777		Sheridan Trip to Scarborough IV i: I’cod, I would not care if he was hang’d.
1793		Prince Hoare Prize II ii: Ecod! It would be a neat trick.
1793		F. Reynolds How to Grow Rich III ii: I’cod it wou’d have done your heart good to see Nicky and I laughing.
1801		M. Edgeworth Belinda (1994) 93: Ecod he talks as if he was a doctor.
1814		I. Pocock John of Paris I i: And such a customer, ecod!
1827		T. Morton A School For Grown Children III i: Ecod, I’ll have a skinfull!
1832		J.K. Paulding Westward Ho! II 190: Old Phiginny, Icod! she never tire, I say dat for she.
1833		‘Chapter of Wants’ in Fun Alive O! 35: The world, ecod, are all in want.
1843–44		Dickens Martin Chuzzlewit (1995) 638: ‘Ecod!’ cried Jonas, with a wild laugh.
1862		‘Soft Place in his Head’ in Prince of Wales’ Own Song Book 70: An’ ecod! she found out my soft place.
1874		M. Clarke Term of His Natural Life (1897) 21: Ecod, Pine [...] you and I are always putting our foot into it!
1914		Joyce ‘Two Gallants’ Dubliners (1956) 51: Ecod! Corley, you know how to take them.
1927		(con. 1835–40) P. Herring Bold Bendigo 12: Ecod! How he would frown to see old Jerry in it at the fair.