We read that Abraham gave all he owned to Isaac:
(ה) וַיִּתֵּ֧ן אַבְרָהָ֛ם אֶת־כׇּל־אֲשֶׁר־ל֖וֹ לְיִצְחָֽק׃
(5) Abraham willed all that he owned to Isaac;
The value of את־כל־אשר־לו is 988 and it corresponds to the Mispar Gadol of the word חפץ, Desire. In the Tree of Life, Desire corresponds to Guevurah, the sefirah that relates to Isaac.