Found this article: Handel's 'Messiah': the first 250 years:

The first performance of Messiah

In his earlier London years Handel had already achieved considerable fame and success, particularly with his operas, but by 1741 things were not so good. Performance costs had risen and he was losing money fast. He was suffering from insomnia, depression and rheumatism. His operas were loudly denounced by influential churchmen as profane and unseemly, and theatres such as the Covent Garden Theatre, which Handel ran at the time, were regarded in some quarters as the low haunts of dubious characters.

So when Handel received an invitation from the Duke of Devonshire to go to Dublin (the capital city and the seat of government of Ireland) and produce a series of charity concerts, he readily accepted. After all, Dublin in the 18th Century was one of the important musical centres of Europe, and he would take Messiah with him and produce it there.

On his way over to Ireland he was delayed at Chester because the winds were wrong for crossing the Irish Sea, so he used the time by rehearsing Messiah with some singers from Chester Cathedral, but the results were not good. On one occasion, having asked the Cathedral organist to recommend any choristers who could sing at sight, Handel auditioned a printer named Janson, who was supposed to have a good bass voice. Janson, however, was useless. Handel in fury said, 'You scoundrel, didn't you tell me that you could sing at sight?' to which the hapless printer replied, 'Yes, Sir, and so I can, but not at first sight!'

On arrival in Dublin, Handel initially ran into a storm of protest from the church authorities. His plan was to give his new oratorio its first performance at the New Musick Theatre in Fishamble Street. But the Dean of St Patrick's Cathedral, Dr Jonathan Swift (author of Gulliver's Travels), initially came out against him, writing as follows:

... whereas it hath been reported that I gave a licence to certain vicars to assist at a club of fiddlers in Fishamble Street, I do hereby annul and vacate the said licence, intreating my said Sub-Dean and chapter to punish such vicars as shall ever appear there, as songsters, fiddlers, pipers, trumpeters, drummers, drum-majors, or in any sonal quality, according to the flagitious aggravations of their respective disobedience, rebellion, perfidy and ingratitude.

Swift must have relented, however, because the performance did take place, on 13 April 1742 with 26 boys and five men from the Cathedral choirs participating. It was a great success. And the fact that it raised money for several charities (a debtors' prison, a hospital and so on) helped to bolster Handel's reputation in Ireland. He remained in Ireland for eight or nine months, and that sojourn was a great help to him in building up his bank balance, which had become severely depleted because of problems in London.

~Masato