Did Donald Trump quote a Nigerian poet, thinking he was reciting an Irish proverb? Sorry to disappoint – but probably not.

Appearing with Irish prime minister Enda Kenny on Thursday, Trump said: “As we stand together with our Irish friends, I’m reminded of that proverb – and this is a good one, this is one I like. I’ve heard it for many many years and I love it.

“Always remember to forget the friends that proved untrue, but never forget to remember those that have stuck by you.”

He added: “A lot of us know that, we know it well. It’s a great phrase.”

Speaking the day before St Patrick’s Day, it’s no wonder Trump decided to pay tribute to Ireland. But this wasn’t a “proverb” anyone from the nation recognised.

Irish tweeters were quick to point out they’d never heard this supposedly famous proverb.

Then, the plot thickened: it turned out the proverb wasn’t a proverb at all – it was a poem. But where exactly did it come from? So far, the source is unclear.

Many on Twitter were thrilled to find the poem seemed to have been written by Nigerian poet Albashir Adam Alhassan. The poem appears under his name on PoemHunter, a website which collects famous poems as well as those submitted by users. Alhassan’s was submitted on 22 January 2013.

But this poem is all over the place. And we’re not just talking random websites festooned with shamrocks and more Irish stereotypes than an Ed Sheeran track. It appears in many motivational and quote collection books.

It’s on page 388 of Crystal Inspirations by Joanne Tuttle, published in 2012. It appears on page 325 of the Speaker’s Quote Book by Roy B Zuck, published in 1997.

The earliest appearance, at least as far as Google Books is concerned, is in volume 31 of the International Stereotypers’ and Electrotypers’ Union Journal, published in 1936 in America.

So how exactly did a poem, whose author we know nothing about, end up being quoted by the president of the United States as an Irish proverb?

Cody Keenan, a speechwriter for Obama, may have hit on the most likely theory:

And indeed, when you google “famous Irish proverb” the poem is included in the top two sites.

So, long story short: the proverb isn’t a proverb, it’s a poem. It’s probably not Irish, given no one in Ireland seems to have heard of it, but we’re not sure where it came from.