Quick question

I know it's stupid of me to ask this question here but I really wanted to ask some of you here something since I don't really have anyone to ask this
So we recently argued cause one side said it's not a sin to lay down and pray(lay down as in sleeping position) it doesn't matter what the position is but if you're praying sincerely from your heart it's not a sin,cause what God sees is our sincereness and our heart While the other side said it's a sin to lay down and pray cause it's a lazy thing,it doesn't show respect.Even if you're sincere you're lazy for laying down and sleeping
We have been arguing on this topic for so long,we still haven't figured out what is what.
Can you guys give your opinions here on whose side is on the right.