We find the incredible report of Bil'am's donkey talking to him! Although we know that animals can communicate, the power of speech is unique to humankind. This is not a privilege or side benefit granted to the homo-sapien, but specifically the direct expression of the different, not just better, mind and soul that humans possess.
We do not find in chazal that G-D bestowed a mind or soul upon the donkey of Bil'am, rather, in pirkei avos, it states that the mouth of Bil'am's donkey was created on erev shabbos. This would seem that the words of the donkey were not a product of its mind at all, but solely from its mouth. How then can the Torah say that the donkey spoke if the words just eminated from its mouth?
Similarly we may ask regarding Bil'am himself. What was the point of G-D placing the words of brachah into Bil'am's mouth if he surely had no intention of blessing the Jews? Wouldn't those words then be quite meaningless? Yet, we see that Balak was greatly upset by the blessings; obviously, he understood the words would be quite effective!
It seems very clear that the spoken word is powerful, regardless of the mindset or complete lack thereof of the speaker!
This is strongly illustrated once more by the fact that G-D did not merely de-activate Bil'am's power to curse the Jews. This indicates that de-activating the power of one's words would be a greater miracle and change of world order than placing different words into Bil'am's mouth!
We often read and hear about the tremendous importance of having proper concentration during tefilah. Without doubt, that is definitely true! However, we must also recognize the great power of every word emanating from our mouths even when spoken absentmindedly!
This applies not only in Torah and prayer but with words used in social settings as well.
Rabbi Avigdor Miller z"tzl had the beautiful custom to quietly bless pedestrians who passed him by on his daily walk. He would also pause in front of the Mirrer Yeshivah daily and bless all of its students and faculty. In accordance with the passuk, "Va'avarchah mivarachekah" - "And I (Hashem says to Avraham) will bless those who bless you", Rabbi Miller said, he would look forward to blessing others so he would be blessed himself.
There can be no better appliction of the above lesson than to actively start blessing others, without concern as to how much we really mean it. If words can do harm, they most certainly can do tremendous good!
T'hiyu Bruchim!