1. Valāhaka Sutta. There are four kinds of rain clouds: those which produce thunder but no rain; those which produce rain but, no thunder; those which produce neither; those which produce both. There are four similar kinds of persons: those that speak but do not act; those that act but do not speak; those that do neither; and those that do both. A.ii.102.
2. Valāhaka Sutta. There are four kinds of rain-clouds (as above) and four kinds of people: those that know the Dhamma but do not understand it; those that do not know it but understand it; those that do neither; those that do both. A.ii.103.