Analysis of information sources in references of the Wikipedia article "Battle of Nájera" in English language version.
There were in this battalion full four thousand knights and squires, excellently armed, and drawn up according to the French manner. Don Tello and his brother don Sancho commanded the second division. There were under them twenty-five thousand lance-men, as well on horse as on foot, who drew up a little behind the division of sir Bertrand, on his left hand. The third, and largest battalion without comparison, was commanded by king Henry himself. There were in it, and drawn up in array, upwards of seven thousand horsemen and forty thousand infantry among the cross-bowmen.
for the Spaniards and Castillians were near one hundred thousand men in arms