Let me just say right off the bat that I have a problem with keeping my mouth shut when it is probably best that I do. Is my saying something every time I feel the urge to do so really that important to God? Speaking the truth in love, even when it seems unloving to the world is certainly important and necessary, is it not? Yes, AND, however, the Lord also wants us to do so with wisdom and compassion and love with the eternal consequences ever before us.
A long while back, a friend in the Lord gave me this illustration to help me understand what I was doing wrong. He said:
Say you have a cat. This cat loves fresh salmon. One day you put down a dish of fresh, yummy salmon for your cat, and your cat decided, for whatever reason, that he wasn't hungry yet. You, on the other hand, decide that it is time for the cat to eat the salmon you have placed before him, and you want him to eat it NOW. So you take the cat by the scruff of the neck and start jamming this yummy salmon down the cat's throat. This cat might never want to eat salmon again, especially if it is coming from you.
Sigh. Wise words.
James 1:26 If any man among you seem to be religious, and bridleth not his tongue, but deceiveth his own heart, this man's religion is vain.
Now having said that, I don't want to confuse the saying or not saying with something that is similar but ever so different. I also see this being done today, and it is just as wrong as saying things that need to be left to the Holy Spirit to convict the person of in His own time. What I mean is, it is also wrong to not say something because one wants to feign being "loving" but it comes out of a fear of losing the other person's affection. We are to speak the truth in love. That doesn't mean going on and on about something when the person stopped listening hours ago. It also doesn't mean not saying anything at all. It is somewhere in the middle. We need to have the wisdom to speak the truth in love, once, maybe twice AT MOST, and then leave it with the Lord to do His work in the life of that person, and just show that person how much you love him in the Lord.
Have I perfected this? No. It is still something the Lord is working with me on, to develop that wisdom of when to speak, and when to STOP IT and let Him do His work...this is difficult for me, extremely so. I go from one extreme (to go on and on about something) to the other (to not say anything at all, and do a "loving act" phoney as can be).
Thankfully, the Lord knows what to do with a few measly loaves and fishes (my feeble and much less than perfect offerings), and make them abound with His good nourishment for the soul. :)