Valmiki Ramayana 4.3.2

कपि रूपम् परित्यज्य हनुमान् मारुतात्मजः ।भिक्षु रूपम् ततो भेजे शठबुद्धितया कपिः॥

kapi rūpam parityajya hanumān mārutātmajaḥ |bhikṣu rūpam tato bheje śaṭhabuddhitayā kapiḥ ||

Our plain-language meaning of this verse is waiting for scholar review.