By the way, does the Bible state that Ishmael ceases to be Abraham's child just because they are not in the same place? So how can Isaac be Abraham's ONLY son at the time that stupid command was given to Abraham?
ksazma neither the Bible nor I ever stated what you are trying to imply above. What you are having problem with is the ability to comprehend. Both book, the bible & Quran mention that Hagar and Ishmael was left in desert/wilderness, after that(I'm not implying immediately) God then spoke to Abraham.
Follow me here, let me simplify this you. You have two sons, one went off to college in South Pole and the other stayed home with you. A man approach you in your house and said, "you should take your son fishing", who would he be referring too? Would it be the one miles away or the one in eye sight / hand reach?
What's bothering the folks like yourself is the phrase "Only Son", which can simply imply the only one left in your camp/tent take him.
But then again, lets look at the scripture:
Genesis 22:2 2 And he said, Take now thy son, thine only son Isaac, whom thou lovest, and get thee into the land of Moriah; and offer him there for a burnt offering upon one of the mountains which I will tell thee of.
Did you notice God was distinct about whom he was referring too? That verse/scripture did not left us hanging in suspense and confusion.