Angels are spirit beings created by God to serve His purposes and to minister to His people:
Are not all angels ministering spirits sent to serve those who will inherit salvation? (Hebrews 1:14).
Angels hear and act upon God's words:
Praise the LORD, you his angels, you mighty ones who do his bidding,
who obey his word (Psalm 103:20).
Some people may think that this only applies to words currently spoken from the throne of God in heaven directly to the angels. But the fact is, His words in the Bible were already spoken from the throne in heaven and they carry the same authority, power, and relevance now as when He first spoke them. Those words are eternal.
Heaven and earth will pass away, but my words will never pass away (Luke 21:33).
When God's words from heaven are spoken in the earth through our faith-filled mouths, God's power is released. Angels hear the words, obey them, and do God’s bidding, fulfilling their job description.