Something to do before Rosh Hashana
Abulafia (who refers to himself as, among other names, Raziel) had been travelling Italy and preparing those willing to listen for the imminent arrival of Mashiach since a revelation he received in 1270, while still in Barcelona. He reached Rome right after Tisha b'Av, but found that the Pope had retired to his country house in Soriano. When word got out that Abulafia was there to convert him, Nicholas III gave orders to burn the Jew as soon as he entered the town.
Abulafia had decided that this particular Pope would be particularly receptive to his particular brand of mysticism. He was also familiar with a Jewish tradition that Mashiach would convert the Pope. And his calculations had led him to conclude that this had to happen in the year 40, i.e. 1280. His very last opportunity was during the last days of that year, just before Rosh Hashana.
So he risked his life, and set off for Soriano, knowing full well that the wood for his burning was already set out in the courtyard of the papal villa. On his arrival, probably August 23rd 1280, he discovered that the Pope had died suddenly the day before. And so his plan, as well as his execution, came to nothing.