Musar על סנהדרין 178:14

3) The third method of acquiring that status of doing מעשים טובים, is performance of the commandment when it involves various degrees of self sacrifice, מסירת נפש. The Mechilta explains this in connection with Exodus 20,6, where G–d promises reward for the next two thousand generations to people who have performed His commandments, whereas in Deut 7,9, the reward is promised for one thousand generations. The difference is due to whether the commandments have been performed out of love for G–d or out of fear of G–d. Isaac is reported to have replied to Ishmael who had boasted of his מסירת נפש when undergoing circumcision at the age of thirteen, a deed Isaac could not match since he had been only eight days old at his own circumcision. He told his half-brother Ishmael that he would offer up all his organs at the עקדה, thus proving even greater self-sacrifice.

G–d answered Satan at that time, that Abraham already had offered such a sacrifice at the time he circumcised himself and again when he circumcised Isaac, seeing that circumcision rates as a major sacrifice. When he did this he fulfilled the commandment of Leviticus 1,2: אדם כי יקריב מכם קרבן, "when someone offers a sacrifice it should be part of you," i.e. part of your very self. We have an allusion to this in Genesis 12,11 ויהי כאשר הקריב לבא מצרימה, when the use of the word הקריב instead of קרב, indicates that he brought himself closer to G–d (see our commentary page 80). G–d compensated the Jewish people for Abraham's devotion at the appropriate time. We know that circumcision itself rates as a major sacrifice from the boast of Ishmael to Isaac that whereas he, Ishmael, had submitted voluntarily to that painful procedure at the age of thirteen, Isaac as an eight day old baby had not suffered, nor had he accumulated a merit for consenting to that act. Isaac responded that if G–d were to ask him to sacrifice his entire body he would be prepared to do so (compare Sanhedrin 89). According to this last version the words אחר הדברים האלה in 22,1 refer to this conversation between Ishmael and Isaac. We will demonstrate that both approaches are true and reflect valid Torah viewpoints.

The second approach is connected with our exegesis of the meal during which Abraham was told about the impending birth of Isaac being itself a sacrifice, since Abraham had already sacrificed himself when he performed circumcision on his own body. This was the reason that Ishmael boasted about his own מסירת הנפש, dedication to G–d, in having his father perform this operation on him without his objecting. Satan found an excuse to malign Abraham for not having offered a sacrifice during the feast he gave after Isaac was born, and also for not offering a bull and ram to G–d directly, instead of to G–d's intermediaries, the angels, during this meal after he had successfully recovered from the circumcision.