Shabat 89B

Here's a midrash that was totally new to me.

"Rebbe Shmuel taught in the name of Rebbe Yochanan.  Why is it written (Isaiah 63): For you are our father for Abraham doesn't know us and Israel doesn't recognize us.  You Hashem are our father, your eternal name is our our Redeemer'?  In the time to come the Holy One Praised be G-d will say to Abraham:  Your children have sinned against me.  He will say before Him:  "Master of the Universe, blot out their names for the sanctification of your Name.  He says of Jacob, who had great sorrow in raising his children,  "Perhaps he will seek mercy on their behalf."  He said to him, "Your children sinned against me."  He said before Him, "Master of the Universe, blot out their names for the sanctification of your Name.  He said, 'The old have no sense, and the young ones have no counsel."  He said to Issac, "Your children sinned against me."  He said before him, "Master of the universe, these are my children and not your children?  When they said, 'We will do' before 'We will hear,' you called them (Exodus 4:22), 'My son my firstborn.'  Now they are my children and not yours?  Furthermore, how much did they sin?  A person's life is 70 years.  Take away [the first] twenty years, where you don't'  punish them; that leaves 50 years.  Take away another 25 years of nights, leaving 25 years.  Take twelve and a half year years, which are eating, praying, and spending time in the toilet, leaving twelve and a  half.  If you can suffer that - great, and if not, let half be on you and half on me.  If you want to say all of it is on me, here I am before you."  They [Israel] spoke and said, "For you are our father."  Issac said to them, "Before you praise me, praise the Holy One Praised  be G-d," and Issac revealed G-d to  their eyes.   They immediately raised their eyes to heaven and said, "You Hashem are our father, your eternal Name is our Redeemer!"