I remember reading that every person is born with an allotted number of words that one may speak during one's lifetime. When this allotment is exhausted, one's life comes to an end. This idea would explain the above verse: God is infinite, but people live in a finite world where everything has its limitations. Some things may be greater, other things may be less, but nothing on earth is infinite. Since the number of words a person may speak must also be finite, we should speak as little as possible simply to extend our lives.
Even if one does not accept this concept as factual, it is an excellent guideline. People on a fixed income will budget themselves carefully, since any unwise expenditures may deprive them of the means to obtain necessities. If we think of our words as being limited, then those squandered in non-essential conversation have become unavailable to us for more important things.
When we discover that we have wasted money, we are likely to become very upset with ourselves. We usually then resolve to be more cautious and discriminating in our future purchases. Let us now think back on how many words we have wasted, and even if they were not outright lies or slander, nevertheless, they were simply useless. We would be wise to make a reckoning of our words as well as our money and similarly resolve not to be wasteful of them in the future.