כִּ֤י אֶ֪לֶף שָׁנִ֡ים בְּֽעֵינֶ֗יךָ כְּי֣וֹם אֶ֭תְמוֹל כִּ֣י יַעֲבֹ֑ר וְאַשְׁמוּרָ֥ה בַלָּֽיְלָה׃
For a thousand years in Thy sight Are but as yesterday when it is past, And as a watch in the night.
Read kabbalistic (mystical) interpretation of Psalms 90:4: and classical mystical sources.