The archdeacon left for Castile, whither the king ordered that there be sent an honourable nobleman, his lord lieutenant, namely João Gomes da Silva, and with him two doctors [of laws]. One was called Martim do Sém and the other Fernão Gonçalves Belágua. The king sent them equipped as was appropriate to their honour and estate, and they took with them a letter which read as follows:

The first term was that in all the wars which your son and all his successors might fight against any people, we and our heirs would aid him with ten galleys fitted out at our expense, and that he and those who came after him would also do the same for us and for our descendants. The second term was that such a commitment would not be recorded in the treaty but simply agreed outside it by our letters and yours, and that any other aid, if it were required, would be given out of the close family ties and friendship existing between both sides and without reference to the said letters; and we would all swear regarding the things contained in them not to disclose them to anyone, except if one side failed to carry out the conditions contained in them; then, the other side could speak of them and make demands without censure at breaking the oath.