Rashi

פחז כמים The impetuosity and the precipitance with which you so hastily showed your wrath, just like water that rushes headlong in its course — therefore אל תותר THOU SHALT NOT BE SUPERIOR— you will not receive all these many prerogatives that were proper to you. And what was this impetuosity which you displayed? כי עלית משכבי אביך, אז חללת BECAUSE THOU WENTEST UP TO THY FATHER S PLACE OF REPOSE; THEN PROFANEDST THOU Him Who hovered over my couch — the Name of the Shechina that used to abide above my couch (Shabbat 55b and Rashi there). פַּחַז is a noun (a segolate noun like נַחַל) and has its accent therefore on the first syllable, and the entire word (both syllables) is punctuated with Patach, for were it the past tense of a verb, half of it (the first syllable) would have been punctuated with Kametz and the other half with Patach, and its accent would have been on the last syllable. יצועי denotes a couch, because it is spread (root יצע) with mattresses and sheets; it occurs in this sense frequently in Scripture: (Psalms 132:3) “Nor go up into the bed that is spread for me (ערש יצועי)” ; (Psalms 63:7) “When I remember thee upon my (יצועי) couch”.