It is a part of some verse of the Bible.....and this particular statement can be interpreted in three different ways i think......

1) A superficial approach would be to take it literally in the support of 'Moral Relativism', in contrast to the absolutism, which states that as no one is objectively right or wrong so no person is to be allowed to judge the morality, behaviour, opinions, personal likes/dislikes etc. of any other person. Otherwise he would be judged in the same way in return.

2)It can also be understood as that one should treat others in the similar way one wants oneself to be treated. The Ethics branch of Philosophy defines this as 'Ethic of Reciprocity'. So one should not treat others in ways that one would dislike to be treated in response.

3)Or it can be expounded as an hyperbole making use of 'divine passive' in the statement i.e. indirect reference to The Almighty. Which means that He or the Creator will treat us in the similar way (here or hereafter or both) we treat others in this world. So don't approach others in any harsh or hostile manner lest you should be treated by Him in the same fashion.

The last one is more logical and easily pursuable i think.