Charles H. Spurgeon on Psalms 91:16

With long life will I satisfy him, etc. The margin here is "length of days; "that is, days lengthened out or multiplied. The meaning is, I will give him length of days as he desires, or until he is satisfied with life; —implying (1) that it is natural to desire long life; (2) that long life is to be regarded as a blessing (comp. Pr 3:2,16 Ex 20:12); (8) that the tendency of religion is to lengthen out life; since virtue, temperance, regular industry, calmness of mind, moderation in all things, freedom from excesses in eating and drinking, —to all of which religion prompts, —contribute to health and to length of days; and (4) that a time will come, even under this promised blessing of length of days, when a man will be "satisfied" with living; when he will have no strong desire to live longer; when, under the infirmities of advanced years, and under his lonely feelings from the fact that his early friends have fallen, and under the influence of a bright hope of heaven, he will feel that he has had enough of life here, and that it is better to depart to another world. And shew him my salvation. In another life, after he shall be satisfied with this life. Albert Barnes.