Le Morte dArthur Vol. 2 Chap. 17.14.
     CHAPTER XIV. How a knight brought unto Sir Galahad a horse, and bade him come from his father, Sir Launcelot.

   SO after, on a Monday, it befell that they arrived in the edge of a forest to-fore a cross; and then saw they a knight armed all in white, and was richly horsed, and led in his right hand a white horse; and so he came to the ship, and saluted the two knights on the High Lord's behalf, and said: Galahad, sir, ye have been long enough with your father, come out of the ship, and start upon this horse, and go where the adventures shall lead thee in the quest of the Sangreal. Then he went to his father and kissed him sweetly, and said: Fair sweet father, I wot not when I shall see you more till I see the body of Jesu Christ. I pray you, said Launcelot, pray ye to the High Father that He hold me in His service. And so he took his horse, and there they heard a voice that said: Think for to do well, for the one shall never see the other before the dreadful day of doom. Now, son Galahad, said Launcelot, since we shall depart, and never see other, I pray to the High Father to conserve me and you both. Sir, said Galahad, no prayer availeth so much as yours And therewith Galahad entered into the forest.

   And the wind arose, and drove Launcelot more than a month throughout the sea, where he slept but little, but prayed to God that he might see some tidings of the Sangreal. So it befell on a night, at midnight, he arrived afore a castle, on the back side, which was rich and fair, and there was a postern opened toward the sea, and was open without any keeping, save two lions kept the entry; and the moon shone clear. Anon Sir Launcelot heard a voice that said: Launcelot, go out of this ship and enter into the castle, where thou shalt see a great part of thy desire. Then he ran to his arms, and so armed him, and so went to the gate and saw the lions. Then set he hand to his sword and drew it. Then there came a dwarf suddenly, and smote him on the arm so sore that the sword fell out of his hand. Then heard he a voice say: O man of evil faith and poor belief, wherefore trowest thou more on thy harness than in thy Maker, for He might more avail thee than thine armour, in whose service that thou art set. Then said Launcelot: Fair Father Jesu Christ, I thank thee of Thy great mercy that Thou reprovest me of my misdeed; now see I well that ye hold me for your servant. Then took he again his sword and put it up in his sheath, and made a cross in his forehead, and came to the lions, and they made semblaunt to do him harm. Notwithstanding he passed by them without hurt, and entered into the castle to the chief fortress, and there were they all at rest. Then Launcelot entered in so armed, for he found no gate nor door but it was open. And at the last he found a chamber whereof the door was shut, and he set his hand thereto to have opened it, but he might not.