וַיְמָאֵ֣ן אָבִ֗יו וַיֹּ֙אמֶר֙ יָדַ֤עְתִּֽי בְנִי֙ יָדַ֔עְתִּי גַּם־ה֥וּא יִֽהְיֶה־לְּעָ֖ם וְגַם־ה֣וּא יִגְדָּ֑ל וְאוּלָ֗ם אָחִ֤יו הַקָּטֹן֙ יִגְדַּ֣ל מִמֶּ֔נּוּ וְזַרְע֖וֹ יִהְיֶ֥ה מְלֹֽא־הַגּוֹיִֽם׃
And his father refused, and said: ‘I know it, my son, I know it; he also shall become a people, and he also shall be great; howbeit his younger brother shall be greater than he, and his seed shall become a multitude of nations.’
Rashi on Genesis
ידעתי בני ידעתי I KNOW IT, MY SON, I KNOW that he is the first-born.
Or HaChaim on Genesis
וימאן אביו ויאמר, His father refused, saying, etc. The reason the Torah uses the word "he refused," is to indicate that Joseph had taken hold of his father's hand to try and place it on Menashe's head.