What is the antecedent of “-hu” in “fa-jaʿalahu ghuthāʾan aḥwā”?

Supplementary Practice 28 — Comparative Rhetoric of Sūrat al-Aʿlā and Sūrat al-Ghāshiyah

• Al-marʿā, the pasture
• Ghuthāʾ, the second object
• Alladhī, the relative pronoun
• Al-aʿlā, the adjective