What is the ruling on a mature girl sitting on her father's lap, on his thighs?

One must be extremely cautious of this act, as it leads to lust and temptation. The Messenger of Allah (peace be upon him) commanded that children be separated in their beds when they reach the age of ten, because this age marks the beginning of each gender's inclination towards the other, and there is a fear of corruption for them. Satan is an enemy to humankind, and what is known as incest has become prevalent.