This orthodoxy is so taken for granted that Sirach can move easily from using God's wrath as a motive for caution with respect to vows to the mundane phenomena of plenty and hunger, wealth and poverty and other changing conditions.
Before making a vow, prepare yourself: and do not be like a man who tempts the Lord. Think of his wrath on the day of deaths and of the moment of vengeance when he turns away his face. In the time of plenty think of the time of hunger; in the days of wealth think of poverty and need. From morning to evening conditions change, and all things move swiftly before the Lord. Sirach 18:23-26
The difference for Sirach compared with earlier wisdom literature is not in his knowledge of God's potential enmity, but rather in the sources of his knowledge. Earlier wisdom thinkers had gleaned their knowledge of God's hazardous activities from observation and experience. As the admonition in Sirach 2:10 probably indicates, Sirach also gained knowledge by reflection upon the experiences mediated through his cultural heritage.
Consider the ancient generations and see: who ever trusted in the Lord and was put to shame? Or who ever persevered in the fear of the Lord and was forsaken? Or who ever called upon him and was overlooked? 94
94 Eliphaz had the same fundamental insight (Job 4:7) as did the (wise) psalmist (Psalm 37:25),