The affix yat comes in the sense of 'praising' after the words 1. revatī 2. jagatīand 3. haviṣya in the Genitive -6th-Case in construction, in the chandas (Vedas).,
The word प्रशस्य means प्रशंसन 'praising, extolling', formed by adding the Krit affix क्यप् to the root, with the force of भाव or 'condition'. Thus रेवत्यम्॑, जगत्य॑म् and हविष्य॑म् 'praising of Revati, Jagati or Havishya'. The word हविष्यम् is thus formed हविषे हिता = हविष्याः 'things fit for offering' i. e. butter &c, (हविष् + यत् 5.1.4) हविष्यानाम् प्रशंसनं = हविष्यम् (हविष्य + यत् 4.4.122) = हविष्य् + यत् the final अ being elided by 6.4.148 = हविष् + यत् the य being elided by 8.4.64.,