וַיִּירָא֙ וַיֹּאמַ֔ר מַה־נּוֹרָ֖א הַמָּק֣וֹם הַזֶּ֑ה אֵ֣ין זֶ֗ה כִּ֚י אִם־בֵּ֣ית אֱלֹהִ֔ים וְזֶ֖ה שַׁ֥עַר הַשָּׁמָֽיִם׃
이에 두려워하여 가로되 두렵도다 이 곳이여 다른 것이 아니라 이는 하나님의 전이요 이는 하늘의 문이로다 하고
Kitzur Shulchan Arukh
You should express grief in the manner of your sleeping. For example, if you are accustomed to sleep on two pillows, you should sleep only on one. Some people have the custom to sleep on the floor during the night of Tishah beAv, and to put a stone underneath their head as a reminder of what was said, "And he took some of the stones of the place etc.," (Genesis 28:11). Our Sages comment that Jacob foresaw the destruction of the Beis Hamikdash and said, "How frightful" etc. (verse 17). It all depends on the person's attitude.2A pregnant woman or any weak (or sick) person is not obligated to do any of these things. (Ibid. 555:7)