His Son Yosef

When Yaakov called Yosef to request that he be buried in Eretz Yisroel, it says that he called “his son Yosef”. We know that Yosef was Yaakov’s son, why was it necessary to underline that fact? (see Ohr Hachaim)

Perhaps this tells us something about the nature of Yosef. The pasuk is telling us that he called for Yosef even had he not been his son, and his son, even were he not Yosef. Yosef was so good-hearted that he would refuse no reasonable request, and even were it not his own father he would see to it that he was buried according to his wish. Yaakov called for he who was his son, and was Yosef too.