这一生地老天荒下一世海枯石烂
[zhè yī shēng dì lăo tiān huāng xià yī shì hăi kū shí làn]
These phrases together mean 'In this life until the earth grows old and the sky turns desolate; In next life until the sea dries up and rocks crumble', symbolizing an eternal love or commitment crossing lives.