Israel, however, had been a wayward flock in the past. This led the writer to warn the people to avoid the sins that had resulted in the wilderness wanderings. At Meribah (lit. strife; Exod. 17:1-7; Num. 20:2-13) and Massah (lit. testing; Exod. 17:1-7) Israel tested God by demanding that He provide for them on their terms. They should have simply continued to trust and obey God. Perhaps the writer mentioned these rebellions and not others because they so clearly reveal the ingratitude and willfulness that finally resulted in God sentencing that generation to die in the wilderness. Their actions betrayed the fact that they had not learned God's ways, namely that He would do what was best for them in His own time and way. That generation could have entered into rest in the land of milk and honey. Likewise believers who fail to follow their Good Shepherd faithfully can look forward to a life of hardship and limited blessing. In view of the urgency of this exhortation the writer began it by calling for action "today."
The writer to the Hebrews quoted verses 7-11 to urge Christians to believe God and move ahead in faith. Not obtaining rest for the Christian means failing to enter into all the blessings that could be ours if we faithfully trusted and obeyed God.
This psalm is a sober reminder that praise needs to connect with trust and obedience. It also anticipates the time when those who follow the Shepherd faithfully will reign with Him in His universal rule over the earth (cf. Ps. 2; 2 Tim. 2:12a; Rev. 3:21; et al.).
