Psalm 96:9, "Worship Yahweh in holy array. Tremble before him, all the earth," is a powerful call to reverence and awe of God. Let's break down its meaning:

"Worship Yahweh": This is a direct command to offer adoration, respect, and honor to God, whose personal name is Yahweh. Worship encompasses more than just singing songs; it involves a wholehearted devotion and submission to God's will.

"in holy array": This phrase is rich in meaning and can be interpreted in a few ways:

Proper attire and preparation: It could refer to the appropriate clothing and physical preparation for approaching God in worship. In ancient times, priests and people often wore special garments and underwent purification rituals before entering sacred spaces.
Holy attitude or disposition: More broadly, it suggests approaching God with a pure heart, a reverent spirit, and a commitment to holiness in one's life. It is more about a mindset of worship, putting aside distractions and focusing on God.
Orderly and structured worship: It might imply worship that is organized, thoughtful, and respectful of God's holiness.

"Tremble before him, all the earth": This speaks to the awe-inspiring power and majesty of God. "Tremble" doesn't necessarily mean being terrified, but rather acknowledging God's supreme authority and feeling a sense of humility and reverence in His presence. "All the earth" emphasizes the universal scope of God's dominion and the call for all people to recognize His sovereignty.

In essence, this verse calls for:

Reverence: Recognizing and respecting God's holiness and power.
Submission: Acknowledging God's authority and willingly submitting to His will.
Humility: Approaching God with a humble and contrite heart.
Universal acknowledgement: Affirming that all people, everywhere, should recognize God's greatness and worship Him.

The verse encourages a worship that is not casual or flippant, but one that is deeply respectful, intentional, and acknowledges the awesome nature of God.