Why doesn't the Chumash record a blessing for Yitzchak?

Question

Yitzchak blesses his two sons.

Ya'acov blesses his twelve sons and even a couple of grandsons.

Even Noach tells of the future of his sons.

Does Avraham ever formally bless Yitzchak? If so, why doesn't the text record the content of the blessing?

One might say he doesn't have to because at the end of his life, Avraham had only 1 son (effectively, as he had sent away his other son, Yishma'el) but the text relates that Avraham had other children and in Bereishit 25:5 says that Avraham gave Yitzchak all that he had, to differentiate what he passed down to Yitzchak from other children. But while the Malbim says that this includes spirituality, the text records no actual blessing.

Is the content of a blessing here unnecessary because the text attests to "kol asher lo" all that was to Avraham? Would this mean that any written up blessing implicitly excludes certain things?

Does that mean that a formalized blessing is only used to divide up or apportion when there is potential for confusion. Blessing is then not about explicitly passing a role or yoke – just about codifying who gets that yoke or only some parts of it?

Answer 1

Rashi to Bereishis 25:11 quotes the Gemara in Sotah 14 that, as Avraham foresaw that Eisav would descend from Yitzchak, he was afraid to give Yitzchak the Brachos, fearing that they would go to Eisav as well. He decided to leave it to HaShem whether Yitzchak should get the Brachos or not, and, indeed, HaShem gave them to Yitzchak in the aforementioned passuk.

Answer 2

Refer to the Targum Yonasan on Bereishis 25:11 which writes:

וּמִן בִּגְלַל דְלָא הֲוָה אַבְרָהָם צָבֵי לִבְרָכָא יַת יִשְׁמָעֵאל בְּגִין כֵּן לָא בְּרִיךְ יַת יִצְחָק דְאִין הֲוָה מְבָרֵךְ לְיִצְחָק וְלָא מְבָרֵךְ לְיִשְׁמָעֵאל הֲוָה נְטִיר לֵיהּ בָּבוֹי וּבָתַר דְמִית אַבְרָהָם בְּרִיךְ יְיָ יַת יִצְחָק וְיָתֵב יִצְחָק סָמִיךְ לְבֵירָא דְאִתְגְלֵי עֲלוֹי יְקַר חַי וְקַיָים דְחָמֵי וְלָא אִתְחָמֵי

And because Avraham had not designed (i.e. felt it appropriate) to bless Yishmael, so too he did not bless Yitzchak; for had he blessed Yitzchak and not Yishmael, he (Yishmael) would have harboured resentment. But, after the death of Avraham, Hashem blessed Yitzchak; and Yitzchak dwelt near the well at which was revealed the glory of the Living and Eternal One, who sees and is not seen.

So it would seem that Avraham avoided formally blessing Yitzchak lest it provoke the ire of Yishmael. When Avraham died, it would seem that Hashem 'formally' blessed him.