What is Isaac Newton's Law of Gravity?

Only one law: There is a force of mutual attraction between any two masses, that is directly proportional to the product of the masses, and inversely proportional to the square of the distance...

Two masses attract each other with a force proportional to the product of the masses and inversely proportional to the square of the distance between their centres of gravity. You did ask!

for every action there is an equal and opposite reaction

the force that pulls 2 objects toward each other,depends on the mass of each object. -nova net answer

Cause he felt like it!.