Hashem tested Avraham in order to evaluate the extent of his faith. Before the trial, Hashem did not know whether or not Avraham would be willing to sacrifice his son for God.
Meaning of "נִסָּה" – Ralbag understand the word to mean "test", a procedure established for purposes of evaluation. Hashem was testing Avraham so as to discern his level of fear and obedience.
Hashem's knowledge – According to Ralbag, Hashem's knowledge is not complete. While He knows all the choices open to a person, He does not know which path the individual will choose to follow.
1 As such, He did not know in advance whether or not Avraham would acquiesce to sacrifice his child upon Hashem's demand.
עַתָּה יָדַעְתִּי כִּי יְרֵא אֱלֹהִים אַתָּה – Ralbag is able to explain this verse according to its simple sense; only "now," after the trial, did Hashem know with certainty how God-fearing Avraham was.
2 The test – Ralbag asserts that Hashem intentionally worded His demand ambiguously so that it could be understood in one of two ways: to sacrifice Yitzchak as an Olah offering, or to take Yitzchak in order to sacrifice an Olah and thereby be educated in the worship of Hashem.
3 Since the second reading is one which a person would only hear if they found the first possibility objectionable, Hashem wanted to see if Avraham was so willing to abide by Hashem's word that he would not even seek out the alternative reading.
4 Avraham's feelings – Ralbag presents an Avraham whose love for Hashem and desire to obey Him was so strong that all else paled in comparison, enabling him to go with ease to sacrifice even a beloved son.
5 Avraham's eagerness to comply with Hashem's words is demonstrated by his early rising to do God's bidding and lack of questioning of the command.
6 Ralbag further claims that the fact that Avraham achieved prophecy while awake proves that even in the moment of the actual slaughter he was neither worried nor sad about the act (as otherwise he would not have been in a state fit for prophecy).
7 "אֱלֹהִים יִרְאֶה לּוֹ הַשֶּׂה לְעֹלָה בְּנִי" – Ralbag maintains that these words of Avraham constitute a prayer
8 that Hashem's command to him actually turn out to mean
9 that the sheep will be the Olah, and not Yitzchak. Ralbag, thus, presents Avraham as recognizing that there was a second way to comprehend Hashem's words, but not being willing to act upon it without a direct clarification by Hashem.
How can Hashem command murder? According to Ralbag, Hashem had never intended for Avraham to actually sacrifice Yitzchak, which is why He worded the command in a way which allowed for the second (and ultimately correct) possibility that Yitzchak was brought to the mountain only to witness an Olah offering. As such, Hashem had never commanded an immoral act. Ralbag's reconstruction is nonetheless difficult since once Hashem intended that Avraham understand that he was to sacrifice his child, the morality of the command (and Avraham's ready agreement) is still in question.
Can Hashem change His word? According to Ralbag Hashem never changed His mind, nor went back on His word. From the beginning it was neither His intention, nor His command to sacrifice Yitzchak.
Benefits for Yitzchak
Avraham, rather than Hashem, was supposed to learn something new from the experience. This position subdivides regarding whether it views the test as beneficial or punitive in nature:
Means to Reward Avraham
Acting on Hashem's directives brought Avraham to new levels of faith, and merited him rewards that he would never have received had Hashem not tested him.
Means to Punish Avraham
The experience was meant to punish Avraham for having made a covenant with the Philistines.
"וַיְהִי אַחַר הַדְּבָרִים הָאֵלֶּה" – Rashbam maintains that these words serve to connect our unit with the immediately preceding one, and are Tanakh's way of linking the two stories.
10 The opening, thus, suggests that Avraham's making of a treaty with Avimelekh is what prompted Hashem's command to Avraham. Hashem was upset that Avraham made peace with the Philistines since thier land was inlcuded in His promise to Avraham, and as such the prhibition ""
Meaning of "נִסָּה" – According to Rashbam, the word "נִסָּה" in our verse means to distress or provoke rather than to test. As evidence of such a usage he points to
Iyyov 4:2. "הֲנִסָּה דָבָר אֵלֶיךָ תִּלְאֶה", and
Shemot 17:7, "עַל רִיב בְּנֵי יִשְׂרָאֵל וְעַל נַסֹּתָם אֶת י"י" where the root is connected to weariness and strife.