Genèse 48:1

ויקח את שני בניו עמו AND HE TOOK HIS TWO SONS WITH HIM — so that Jacob would bless them before his death.

And after these things it was told Joseph, Behold, thy father is lying ill. And he took his two sons with him., Menasheh and Ephraim.

ויאמר ליוסף, a third person told him. We find similar constructions, the subject not only not being named but not being identified at all, in verse 2 of our chapter, i.e. ויגד. The Torah does not bother to inform us who was the one that conveyed this information.

ויאמר, whoever it was who said it. It is reasonable to assume that it was one of the brothers who traveled to the capital to inform Joseph that his father had taken ill.

ויאמר ליוסף, “he said to Joseph;” according to our sages, the subject in this verse was Ephrayim, who informed his father of Yaakov’s illness; (Tanchuma section 6 on this portion) Rabbi Moshe adds that there is an oblique hint of this in the text, seeing that the letters in the word ויאמר and the word אפרים when reading the alphabet backwards, starting with the letter ת, are in the relative same position as when read from the right to left, i.e. the letter ו in the word ויאמר is the sixth letter in the alphabet when read from right to left, whereas the letter פ is in the sixth place when the alphabet is read from left to right commencing with the latter ת. (the other letters are identical) What we learn from this is that whereas Joseph was not a frequent visitor in the province of Goshen where his father resided, his sons spent much more of their time with their grandfather, so that they were aware of any changes in the state of his health. The words ויקרא לבנו ליוסף, “he called for his son, for Joseph,” i.e. sent a messenger to ask for his presence, indicated that he did not want to wait for Joseph’s next visit. I have heard from Rabbi Sh’muel of blessed memory that the reason that Joseph did not frequently visit his father was that he was afraid that Yaakov would ask him how he had come to be in Egypt in the first place, in which case he would have had to tell him that his brothers had sold him, etc., as a result of which his father would have cursed the brothers. This in turn would have spelled the destruction of the civilised world, seeing that when he had cursed Rachel quite unintentionally, Rachel died prematurely as a result, although the teraphim of Lavan had never even been found. We cannot even imagine what the result of Yaakov cursing ten of his twelve sons would have meant.