The Talmud explains the reason that G-d expressed His request to Avraham in this particular manner:
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R. Shimon ben Abba said: “‘Na’ can only denote entreaty. This may be compared to a king of flesh and blood who was confronted by many wars, which he won by the aid of a great warrior. Subsequently, he was faced with a severe battle. Thereupon he said to him, ‘I pray thee, assist me in battle, that people may not say, there was no reality in the earlier ones.’ So also did the Holy One, blessed be He, say unto Avraham, ‘I have tested you with many trials and you withstood them all. Now, be firm, for My sake in this trial, that men may not say, there was no reality in the earlier ones.’”
Talmud, Sanhedrin 89b
Were Avraham not to have passed this final test of being prepared to offer his son as a sacrifice before G-d, his entire dedication to G-d would have been uncertain. People would say that all the previous tests of Avraham were meaningless. G-d therefore was particularly interested that Avraham withstand this test and therefore beseeched him to go through with it. From the fact that we see G-d’s concern “that men may not say, there was no reality in the earlier ones,” it leads us to understand that their words would have had merit, were Avraham not to have passed this test.
However, the accusation that would have been leveled against Avraham—were he not to have overcome this challenge—does not seem to make sense. Why would his failure to stand up to the last test be indicative that all the rest of the nine tests were meaningless?
One can imagine that this trial of sacrificing his son on an altar before G-d was supremely difficult. Seemingly though, the only thing that his failure to overcome the last test would express, would be that although extremely dedicated, his self-sacrifice was not to the degree that he would slaughter his son borne to him in old age. How would a failure to pass an extremely difficult hurdle indicate that all the other amazing feats that Avraham performed, indicating his commitment to G-d, were meaningless?!
