Psalm 23/Notes/Lexical.V. 4.76057

• בְּגֵ֪יא ("in the valley"): The word "valley" occurs only here in the psalms. As Briggs and Briggs noted, "The hill country of Judah is broken up by narrow and precipitous ravines, or wadys, difficult to descend and ascend, dark, gloomy, and abounding in caves, the abode of wild beasts and robbers (v. 1 S. 24). To pass through these wadys was still more difficult than to find the right path over the hills." Therefore, the "valley of darkness" is a valley where the danger of death existed because of wild animals and robbers.
• The word translated here as darkness (צַלְמָוֶת) is disputed. For an in-depth discussion of the issue, see The Meaning of צלמות in Ps 23:4.
• To comfort (נחם) is associated with bringing relief to someone by providing assurance, security, and safety. In the case of Psalm 23, YHWH's rod and staff comfort the psalmist; i.e., they give the psalmist both protection and guidance. For more information, see the Venn diagram of the verb to comfort (נחם) below: