There shall no evil befall thee - The Chaldee Paraphrase has, "The Lord of the world answered and said, 'There shall no evil befall thee,'" etc. The sentiment, however, is that the psalmist could assure such an one, from his own personal experience, that he would be safe. He had himself made Yahweh his refuge, and he could speak with confidence of the safety of doing so. This, of course, is to be understood as a general truth, in accordance with what has been said above.
Neither shall any plague come nigh thy dwelling - On the word rendered "plague" here נגע nega‛ - see Psalm 38:12, note; Psalm 39:11, note. It is not the same word which is used in Psalm 91:6, and translated "pestilence;" and it does not refer to what is technically called the "plague." It may denote anything that would be expressive of the divine displeasure, or that would be sent as a punishment. The word rendered "dwelling" here means a tent; and the idea is, that no such mark of displeasure would abide with him, or enter his tent as its home. Of course, this also must be understood as a general promise, or as meaning that religion would constitute a general ground of security.

There shall no evil befall thee,.... The evil of sin cleaves to the best of saints, the evil of temptations besets them, and the evil of afflictions comes upon them, as chastisements from the Lord; for they must expect to receive evil, in this sense, as well as good, from his hands; but the evil of punishment never touches them; and therefore, when any public calamity befalls them in common with others, yet not as an evil of punishment; it is not an evil to them, it is for their good:
neither shall any plague come nigh thy dwelling; how should it, when they dwell in God, and have made him, the most High, their habitation (u); Psalm 91:1 otherwise it may come nigh their temporal dwellings; See Gill on Psalm 91:7 though it may not enter into them; and, should it, yet not as an evil, or by way of punishment; see Proverbs 3:33.
(u) "excelsum posuisti habitaculum tuum", Pagninus, Montanus, De Dieu, Gejerus.