Thanks for bringing that up, but it struck me as not sounding like Lao Tzu, so I looked it up. It is actually the Tasoist sage Chuang Tzu, or Zhuangzi, to be more accurate. Hope you don't mind a little elaboration on the story, below:
Zhuangzi himself shows indifference toward death and decries the common practice of mourning because the mourner assumes knowledge of the unknown and pretends his dislike of it. In contrast, by his understanding of the nature of things, the sage is no longer affected by external factors and the changes of the world. On this passage the great commentator Kuo Hsiang comments: When ignorant, he felt sorry. When he understood, he was no longer affected. This teaches man to disperse emotion with reason.
When Zhuangzis wife died, his friend Hui Shih found Zhuangzi sitting on the ground, singing and banging on pots. On asking him how he could be so unfeeling to his wife, he was told by Zhuangzi: When she had just died, I could not help being affected. Soon, however, I examined the matter from the very beginning. At the very beginning, she was not living, having no form, nor even substance. But somehow or other there was then her substance, then her form, and then her life. Now by a further change, she has died. The whole process is like the sequence of the four seasons, spring, summer, autumn, and winter. While she is thus lying in the great mansion of the universe, for me to go about weeping and wailing would be to proclaim myself ignorant of the natural laws. Therefore I stopped!
https://philosophynow.org/issues/27/Death_in_Classical_Daoist_Thought