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?