Ibn Ezra on Numbers 25:17

צרור. שם הפועל כמו זכור את יום השבת: HARASS. Tzaror (harass) is an infinitive.³⁹It is vocalized with a kamatz. An imperative is vocalized with a sheva. It is like the word zakhor⁴⁰Which is also vocalized with a kamatz rather than with a sheva. (remember) in Remember the sabbath day, to keep it holy.