BG 1.12-13 'A śloka a day' #SAH #SanskritGrammar

तस्य संजनयन् हर्षं कुरु-वृद्धः पितामहः |
सिंह-नादं विनद्योच्चैः शङ्खं दध्मौ प्रतापवान् ||12||
ततः शङ्खाश् च भेर्यश् च पणवानकगोमुखाः |
सहसैवाभ्यहन्यन्त स शब्दस् तुमुलो 'भवत् ||13||

tasya saṃjanayan harṣaṃ kuru-vṛddhaḥ pitāmahaḥ | siṃha-nādaṃ vinadyoccaiḥ śaṅkhaṃ dadhmau pratāpavān ||12||

tataḥ śaṅkhāś ca bheryaś ca paṇavānakagomukhāḥ |

sahasaivābhyahanyanta sa śabdas tumulo 'bhavat ||13||

तस्य his, of him (masc, genitive, sing)
हर्षम् (masc, accusative, sing) joy, delight
संजनयन् (causative, present participle, masc, nom, sing) bringing forth, producing; from sam√jan

कुरु-वृद्धः the aged Kuru

पितामहः grand-father, lit. great father  (masc, nom,sing)
प्रतापवान् full of dignity, full of power, energy (masc, nom, sing adj) for पितामहः
उच्चैः by loudly, by high (instrumental pl adverb)
सिंह-नादम् roar of a lion (masc acc, sing)
विनद्य sounding forth (gerund from vi√nad)
शङ्खम् conch (masc, acc, sing)
दध्मौ he blew (3rd person sing, past perfect from √dhamā)

ततः then
शङ्खाः the conches (masc, nom, pl)
च and
भेर्यः kettle-drums (fem, nom pl)
च and
पणवानकगोमुखाः (पणव+अनक+गोमुखः) cymbals, drums, trumpets (masc, nom, pl)
सहसा  suddenly (neuter, instrumental, sing)
एव indeed, only (metrical filler!)
अभ्यहन्यन्त were struck (3rd person, pl, past imperfect, passive abhi√han)* Pl see table below
सः the (masc, nom, sing)
शब्दः sound ((masc, nom, sing)
तुमुलः tumultuous (masc, nom, sing, adj) [note cognate]
अभवत् it was, it became (3rd sing, past imperfect from √bhū)

Table 1: *अभि+अहन्यन्त = अभ्यहन्यन्त​