Arcana Coelestia #4216
4216. 'And blessed them' means the resulting joy. This is clear from the meaning of 'blessing' as heartfelt desires for their happiness, dealt with in 3185, and so as giving evidence of joy when one is going away.
Arcana Coelestia #533
533. Since nothing further is mentioned about Lamech apart from the fact that be beget sons and daughters, who are the conceptions and births of such a Church, there is no need to pause any longer over him. What these births, or sons and daughters, were, becomes clear from the Church, for the character of a Church determines that of its offspring. Both those Churches called Methuselah and Lamech breathed their last just before the flood.