21 When the angel of the LORD did not show himself again to Manoah and his wife, Manoah realized that it was the angel of the LORD.

Read Judges 13:21 Using Other Translations

But the angel of the LORD did no more appear to Manoah and to his wife. Then Manoah knew that he was an angel of the LORD.
The angel of the LORD appeared no more to Manoah and to his wife. Then Manoah knew that he was the angel of the LORD.
The angel did not appear again to Manoah and his wife. Manoah finally realized it was the angel of the LORD,