Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 17: Brahmā Orders the Demigods to Incarnate and Assist Rāma
Text 1.17.12

धनदस्य सुतः श्रीमान्वानरो गन्धमादनः।
विश्वकर्मा त्वजनयन्नलं नाम महाहरिम्॥

dhanadasya sutaḥ śrīmān vānaro gandhamādanaḥ
viśvakarmā
tv ajanayan nalaṁ nāma mahā-harim

dhanadasya = of Kuvera, the treasurer of the demigods; sutaḥ = was the son; śrīmān = the prosperous; vānaraḥ = monkey; gandhamādanaḥ = Gandhamādana; viśvakarmā tu = Viśvakarmā; ajanayat = gave birth; nalam = Nala; nāma = named; mahā-harim = to the great monkey.

The prosperous monkey Gandhamādana was the son of Kuvera, the treasurer of the demigods. Viśvakarmā gave birth to the great monkey named Nala.

Nala was great since he was expert in construction for all purposes.