TAKE NOW THY SON, THINE ONLY SON. Since Isaac was the son of the mistress and he alone was to be the one to carry his name, He called him Abraham's only son. The description was for the purpose of magnifying the command, thus saying: "Take now thy only son, the beloved one, Isaac, and bring him up before Me as a burnt-offering.⁠"

MORIAH. Rashi comments: "This is Jerusalem, and we find it in the book of Chronicles: To build the house of the Eternal at Jerusalem on mount Moriah.⁠¹ Our Rabbis have explained that it is called Moriah (instruction) because from the Temple built there on that mountain, instruction came forth to Israel.⁠² Onkelos translated it as "the land of Worship.⁠" This he derived on the basis of reference to the burning of incense, which contained mor³ (myrrh) and other spices, [as part of the Divine Service].⁠"
Now if so, [i.e., if this be the explanation of the name Moriah], the meaning of the verse will then be, "Go into the land which will be called Moriah.⁠" Or it may be that it was always called so on account of the future. In Bereshith Rabbah,⁠⁴ the Sages have said thus: "The Rabbis say, Go into the land of Moriah means into the land where incense will be offered on the altar of G-d, even as it is said, I will get me to the mountain 'hamor' (of myrrh).⁠"⁵ But the opinion of Onkelos, who said "the land of worship,⁠" does not appear to be based on the myrrh in the incense, as Rashi said, for the word "service" does not refer to one of the species used in one of the Divine Services. Besides, why did not Onkelos say, "to the land of the incense of spices?⁠" Instead, Onkelos' intent is to say, "in the land in which they will worhip G-d.⁠"
Onkelos thus matched that which the Sages interpreted in Pirkei d'Rabbi Eliezer, where they said,⁠⁶ "The Holy One, blessed be He, showed Abraham the altar with a finger. He said to him, 'This is the altar on which the first man sacrificed. This is the altar on which Cain and Abel sacrificed. This is the altar on which Noah and his sons sacrificed.' For it is said, And Abraham built 'hamizbei'ach' (the altar) there,⁠⁷ mizbei'ach (an altar) is not written here, rather, hamizbei'ach (the altar). This is the altar on which the predecessors have sacrificed.⁠" Thus far [is the interpretation of Pirkei d'Rabbi Eliezer]. And the name Moriah the Rabbis derived from the word mora (fear), for there the people feared G-d and worshipped Him.
The correct interpretation, in line with the plain meaning of Scripture, is that the name Moriah is like the expression, To the mountain of myrrh, and to the hill of frankincense,⁠⁸ for on that mountain [Moriah] are found myrrh, aloes, and cinnamon,⁠⁹ even as the Rabbis have said:⁠¹⁰ "Cinnamon grew in the Land of Israel, and goats and deers ate of it.⁠" Or it may be that it was so called in praise of the Land of Israel.⁠¹¹
Now here Scripture calls the name of the land, the land of Moriah, and there [in the book of Chronicles, mentioned above],⁠¹² it appears that only the Temple mount was called mount Moriah. Perhaps, the city¹³ was called by the name of that mountain which it contains, [and the name "land of Moriah" means] the land which contains the Moriah, but it was the mountain alone that was called Moriah. Now Abraham knew the land but did not know the mountain. Hence G-d told him to go to the land of Moriah, and He will there show him one of the mountains which is called by that name. He commanded him to offer up his son in that place for that is the mountain which G-d hath desired for His abode,⁠¹⁴ and He wanted the merit of the Akeidah (the Binding of Isaac) to be in the sacrifices forever, as Abraham said, The Eternal seeth.⁠¹⁵ Moreover, for His righteousness' sake,⁠¹⁶ He increased the scope of the trial and wanted Abraham to do it after walking three days. Had Abraham been commanded to do so suddenly at his place, his deed would have been performed in haste and confusion, but since it was done after walking for days it was thus performed with reflection of mind and counsel. And so did the Rabbis say in Bereshith Rabbah:⁠¹⁷ "Rabbi Akiba said, 'G-d surely tried [Abraham with a clear-cut situation] so that people should not say that He confounded him and confused him and he did not know what to do.'"