谁把天荒说成地老谁把海枯当作石烂
[shéi bă tiān huāng shuō chéng dì lăo shéi bă hăi kū dāng zuò shí làn]
It refers to eternal vows made between lovers that nothing can separate them. 'Till the end of time and till the sea goes dry' imply undying love and faithfulness.