The phrase is well known, the poem not so much; in fact I have never seen it in any of the collections of funeral readings. The English poet Ernest Dowson died in 1900 at 32 years old. He was no stranger to loss and mourning. He leaves us this beautiful short piece:
They are not long, the weeping and the laughter,
Love and desire and hate;
I think they have no portion in us after
We pass the gate.
They are not long, the days of wine and roses:
Out of a misty dream
Our path emerges for a while, then closes
Within a dream.