The affix rūpya denotes that which from something has originated when it is added to a word denoting 'cause' or to the name of a man viewed as a cause.,
The word मनुष्य is used meaning 'men as causes.' हेतु means cause or instrument. Thus समादागतं = समरूप्यम् or समीयम् by छ of 4.2.138 meaning 'what proceeds from a like cause.' So also विषमरूप्यम् or विषमीयम् ॥ So of men also देवदत्तरूप्यम् or दैवदत्तम् 4.1.83 'what originates with देवदत्तः', यज्ञदत्तरूप्यम् or यज्ञदत्तम् ॥
The word हेतुमनुष्येभ्यः is in the plural in the sutra, indicating that svarupavidhi 1.1.68 does not apply here.
In denoting हेतु, there is employed the Instrumental case as taught in 2.3.23: and according to the jnapaka in the present sutra, the Ablative case may also be employed in denoting a हेतु, ॥ Or the use of the ablative case in the sense of हेतु, may be explained by 2.3.25.,