Vayera Patriarchs (07) Vol. 25 page 86 ff. Yitzchok’s Bris is superior not only to Yishmael’s but to Avrohom’s as well. Avrohom’s Bris was from higher than reason, but his 99 years of preparation cover this over, and the idea that it is entirely from Hashem is not obvious.

Vayera Patriarchs (07) Likutei Sichos Vol 25 p 86 ff Yitzchok’s Bris is superior not only to Yishmael’s but to Avrohom’s as well. Though Avrohom’s Bris was from higher than reason, but his 99 years of preparation cover this over and the idea that it is entirely from Hashem is not obvious.