ब्रह्मणः सोम्य ते पादं ब्रवाणीति ब्रवीतु मे भगवानिति तस्मै होवाच पृथिवी कलान्तरिक्षं कला द्यौः कला समुद्रः कलैष वै सोम्य चतुष्कलः पादो ब्रह्मणोऽनन्तवान्नाम ॥ ४.६.३ ॥
In plain words
"Let me tell thee a foot of Brahman, my dear." "Tell me, sir." He said to him, "The earth is a portion, the middle region is a portion, the sky is a portion, the ocean is a portion. This, my dear, is the four-portioned foot of Brahman, whose name is the Endless.