כִּֽי־קָצַ֥ר הַמַּצָּ֖ע מֵֽהִשְׂתָּרֵ֑עַ וְהַמַּסֵּכָ֥ה צָ֖רָה כְּהִתְכַּנֵּֽס׃
For the bed is too short for a man to stretch himself; And the covering too narrow when he gathereth himself up.
Read kabbalistic (mystical) interpretation of Isaiah 28:20: and classical mystical sources.