Upon

السلام عليكم
I was just reflecting on something and I realised the difference between saying
و ما انزل الى ابرهيم ...

And what was revealed TO Abraham a.s....

و ما انزل على ابرهيم ...
And what was revealed UPON Abraham a.s.....

They both are almost identical in meaning but the subtle difference is that الى implies something Abraham a.s. was aware of receiving whereas على implies something Abraham a.s. was unaware of receiving.

So if I say السلام إليكم peace be to you ...I am asking for the peace to be given to you while you are aware of it...

But if I say السلام عليكم peace be upon you... I am asking for peace to be given to you even while you are unaware of it