This old saying is all too true, but not appreciated by most of us in how we deal with life. It goes with the dictum ‘Do unto others as you would they do unto you’. It is even apparent in the Lord’s Prayer ‘Forgive us our sins as we would forgive those who sin against us’; that is in the way we forgive others, so forgive us. Admittedly I have yet to hear a sermon on the latter instruction being interpreted in this way, but you can surely see that such an interpretation is valid even if you may not agree with it.
The way we behave to others will come back to us one way or another, generally magnified in its effect.