Responsa sobre Isaías 51:24

They answered:"Reason is not with the aged, and counsel is not with the young." (Shabbat 89b:4) "For Abraham knows us not, Israel does not recognise us" (Isaiah 63:16), rather "my covenant will be made with Isaac." (Genesis 17:21), "I have singled him out," (Isaiah 51:2) "and will give him the birthright," (Psalms 89:28) "and he shall be blessed." (Genesis 27:33)^*These verses seem to support Isaac, i.e, R. Isaac Alfasi, over the Abraham and Jacob, perhaps referring to Rabbeinu Tam.

They responded to the first question: "Lift your hands to the sacred!" (Psalms 134:2) Namely, wash your hands whenever you want to speak sacred words or study Torah. "And bless God!" (ibid.) - with the blessing instituted for washing hands. As for the second question, they responded: Do you not know that four need to give thanks (Berachot 54b:12), and this includes one who was sick. And none are more sick than such a person [who relieves themself], as it says (Isaiah 51:14): "Quickly the crouching one is freed."²cf. Rashi on Isaiah 51:14