It was on this occasion, we are told, that Charlemagne, fearing for Roland when he saw the strength of Oliver, vowed a pilgrimage to Jerusalem should his nephew escape alive.
[Sidenote: Charlemagne's pilgrimage to Jerusalem.] The fulfillment of this vow is described in "Galyen Rhetore." Charlemagne and his peers reached Jerusalem safely in disguise, but their anxiety to secure relics soon betrayed their identity.

The King of Jerusalem, Hugues, entertained them sumptuously, and, hoping to hear many praises of his hospitality, concealed himself in their apartment at night.

The eavesdropper, however, only heard the vain talk of Charlemagne's peers, who, unable to sleep, beguiled the hours in making extraordinary boasts.

Roland declared that he could blow his horn Olivant loud enough to bring down the palace; Ogier, that he could crumble the principal pillar to dust in his grasp; and Oliver, that he could marry the princess in spite of her father.
The king, angry at hearing no praises of his wealth and hospitality, insisted upon his guests fulfilling their boasts on the morrow, under penalty of death.

He was satisfied, however, by the success of Oliver's undertaking, and the peers returned to France.