While discoursing to the group, Baba explained to them:
Of the three most important things to be eliminated before attaining God-Realization – greed, lust and backbiting – backbiting is the worst and most disastrous. One can overcome greed, and even lust, though both are very hard to get rid of; but by far the worst, and most difficult habit of all to eliminate, is that of speaking ill of and trying to find faults or flaws in others.
And why must it be eliminated? Because this particular act or vice incurs the burden of sins or sanskaras of others, which is spiritually very derogatory and reactionary.
–www.lordmeher.org, p2359
Here is an old post, where Baba indicated that it is very difficult to erase sanskaras created by backbiting: