The LORD said to Abram, “Go forth from your native land and from your father’s house to the land that I will show you.

....It is possible that Terah’s son Nahor left for Haran before his father. On the other hand he may have left for Haran after his father went there. It appears to me that the portion containing the command, Get thee out of thy country, and from thy kindred, and from thy father’s house, unto the land that I will show thee (Gen. 12:1), was conveyed to Abraham before what is recorded in the verse reading, And Terah took Abram…Lot…Sarai…to go into the land of Canaan. Similarly elsewhere the Pentateuch states, And the Lord spoke unto Moses in the wilderness of Sinai, in the tent of meeting, on the first day of the second month, in the second year after they were come out of the land of Egypt (Num. 1:1); and then, And it came to pass in the first month in the second year (Ex. 40:17). Proof of the above is found in And they went forth…to go into the land of Canaan (v. 31). When Terah came to Haran, the place found favor in his eyes. He settled there and eventually died there. The general rule thus is that the Bible does not always list events in chronological order.

OUT OF THY COUNTRY, AND FROM THY BIRTHPLACE. Rashi wrote, “But had he not already departed from there together with his father and reached as far as Haran? But thus, in effect, did the Holy One, blessed be He, say to him, ‘Go still further away from thy father’s house.’”
And Rabbi Abraham ibn Ezra explained the verse as follows: “And G-d had already said to Abram, ‘Get thee out of thy country,’ since this command came to him when he was still in Ur of the Chaldees, and there He commanded him to leave his country, his birthplace and his father’s house, in which he was.”
But this is not correct, for if so, it would follow that Abram was the central figure in the journey from his father’s house by command of G-d, while Terah his father voluntarily went with him. Yet Scripture says, And Terah took Abram his son, which teaches us that Abram followed his father and that it was by his counsel that Abram went forth from Ur of the Chaldees to go to the land of Canaan! Furthermore, [according to Ibn Ezra, who says that the above command came to Abram when he was still in Ur of the Chaldees], the verse stating, And I took your father Abraham from beyond the river and led him throughout all the land of Canaan, should have stated, “And I took your father from Ur of the Chaldees and led him throughout all the land of Canaan,” for it was from there that he was taken, and it was there that he was given this command. In addition, the following difficulty may be put to Rashi and Ibn Ezra: when Abraham commanded Eliezer to get a wife for his son, he said to him, ‘But thou shalt go unto my country and to my birthplace,’ and he went to Aram-naharaim, to the city of Nahor. If so, that is his “country” and his “birthplace!” And there, Scripture further says [when Eliezer recounts Abraham’s charge to him], But thou shalt go unto my father’s house and to my family, thus clearly indicating that there (in Mesopotamia) were his father’s house and his family which is “his kindred.” This is not as Rabbi Abraham ibn Ezra erred in interpreting, “Unto my country, Haran; and to my birthplace, Ur of the Chaldees.” Now since Ibn Ezra says here that in Ur of the Chaldees it was said to Abraham, Get thee out of thy country, and from thy kindred, and from thy father’s house, Abraham would thus have many countries! But the essential principle you already know from what we have written in the preceding Seder, namely, that Haran is Abraham’s country, and there is his birthplace, it having always been his father’s country, and there Abraham was commanded to leave them. In Bereshith Rabbah, the Rabbis similarly say “Lech lecha: one departure from Aram-naharaim, and one from Aram-nahor.”
The reason for mentioning out of thy country, and from thy birthplace, and from thy father’s house is that it is difficult for a person to leave the country wherein he dwells, where he has his friends and companions. This is true all the more if this be his native land, and all the more if his whole family is there. Hence it became necessary to say to Abraham that he leave all for the sake of his love of the Holy One, blessed be He.
UNTO THE LAND THAT I WILL SHOW THEE. He wandered and went about from nation to nation, from kingdom to another people, until he came to the land of Canaan, where He said to him, Unto thy seed will I give this land. Then the promise, Unto the land that I will show thee, was fulfilled, and Abraham tarried and settled there. The verse which states, And they went forth to go into the land of Canaan, means that he was not heading for Canaan for the purpose of settling there since he did not as yet know that he had been commanded concerning this land. Rather, the righteous one set his goal towards the land of Canaan for that was his intention as well as that of his father when they originally set forth from Ur of the Chaldees. This is the reason why Abraham later said, And it came to pass, when G-d caused me to wander from my father’s house: he was indeed gone astray like a lost sheep.
It is possible to say that Abraham knew from the first that the land of Canaan was “the inheritance of the Eternal,” destined that His special Providence be bestowed upon it, and he believed that the Divine promise, Unto the land that I will show thee, alluded to the land of Canaan either in its entirety or to one of all those lands [which together comprise Canaan]. He set his direction towards the land of Canaan generally for [he was certain that] there was the land which He would indeed show him.