Halakhah for Sanhedrin 208:4

(איכה א, ב) בכה תבכה בלילה שתי בכיות הללו למה אמר רבה אמר רבי יוחנן אחד על מקדש ראשון ואחד על מקדש שני בלילה על עסקי לילה שנאמר (במדבר יד, א) ותשא כל העדה ויתנו את קולם ויבכו העם בלילה ההוא

Another meaning: whoever weeps at night, the stars and constellations weep with him. Another meaning: whoever weeps at night, he who hears him, weeps [in sympathy]. It happened that the child of a neighbour of R. Gamaliel died, and she was weeping for him at night. R. Gamaliel, on hearing her, wept in sympathy with her, until his eyelashes fell out. On the morrow, his disciples discerned this, and removed her from his neighbourhood. And her tears are on her cheeks.<span class="x" onmousemove="('comment',' Lam. I, 2. ');">⁹</span> Rabbah said in R. Johanan's name: As a woman who weeps for the husband of her youth, as it is written, Lament like a virgin girded with sackcloth for the husband of her youth.<span class="x" onmousemove="('comment',' Joel I, 8. ');">¹⁰</span>

Sefer HaChinukh