SB 12.4.4
esa naimittikah proktah
pralayo yatra visva-srk
sete ’nantasano visvam
atmasat-krtya catma-bhuh
Translation:
This is called the naimittika, or occasional, annihilation, during which the original creator, Lord Narayana, lies down upon the bed of Ananta Sesa and absorbs the entire universe within Himself while Lord Brahma sleeps.