Srimad Bhagavatam Canto 08, Chapter 24, Text 32

SB 8.24.32

sri-bhagavan uvaca
saptame hy adyatanad urdhvam
 ahany etad arindama
nimanksyaty apyayambhodhau
 trailokyam bhur-bhuvadikam
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The Supreme Personality of Godhead said: O King, who can subdue your enemies, on the seventh day from today the three worlds — Bhuh, Bhuvah and Svah — will all merge into the water of inundation.
Srimad Bhagavatam Canto 08, Chapter 24, Text 31
Srimad Bhagavatam Canto 08, Chapter 24, Text 33