To swear by heaven is the same as swearing by God's throne and by the one who sits on that throne.
The LORD is sitting in his sacred temple on his throne in heaven. He knows everything we do because he sees us all.
The LORD said: Heaven is my throne; the earth is my footstool. What kind of house could you build for me? In what place will I rest?
But I tell you not to swear by anything when you make a promise! Heaven is God's throne, so don't swear by heaven.
“Heaven is my throne, and the earth is my footstool. What kind of house will you build for me? In what place will I rest?