SB 10.43.1

śrī-śuka uvāca
atha kṛṣṇaś ca rāmaś ca
 kṛta-śaucau parantapa
malla-dundubhi-nirghoṣaṁ
 śrutvā draṣṭum upeyatuḥ
Word for word: 
śrī-śukaḥ uvāca — Śrī Śukadeva Gosvāmī said; atha — next; kṛṣṇaḥ — Kṛṣṇa; ca — and; rāmaḥ — Balarāma; ca — also; kṛta — having carried out; śaucau — purification; param-tapa — O chastiser of enemies; malla — of the wrestling match; dundubhi — of the kettledrums; nirghoṣam — the resounding vibration; śrutvā — hearing; draṣṭum — to see; upeyataḥ — They approached.
Translation: 
Śukadeva Gosvāmī said: O chastiser of enemies, Kṛṣṇa and Balarāma, having executed all necessary purification, then heard the kettledrums resounding at the wrestling arena, and They went there to see what was happening.
Purport: 

Śrīla Śrīdhara Svāmī explains the words kṛta-śaucau, “having executed all necessary purification,” as follows: “Two days previously, Kṛṣṇa and Balarāma had executed Their purification, Their relief from offense [by performing heroic deeds]. The Lords reasoned: ‘Even after We have made Our power known by breaking the bow and by performing other feats, Our parents have still not secured freedom. Kaṁsa is again trying to kill them. Therefore, although he is Our maternal uncle, it will not be wrong for Us to kill him.’ They assured Their offenselessness by this reasoning.”