SB 10.2.23

iti ghoratamād bhāvāt
 sannivṛttaḥ svayaṁ prabhuḥ
āste pratīkṣaṁs taj-janma
 harer vairānubandha-kṛt
Word for word: 
iti — thus (thinking in the above-mentioned way); ghora-tamāt bhāvāt — from the most ghastly contemplation of how to kill his sister; sannivṛttaḥ — refrained; svayam — personally deliberating; prabhuḥ — one who was in full knowledge (Kaṁsa); āste — remained; pratīkṣan — awaiting the moment; tat-janma — until the birth of Him; hareḥ — of the Supreme Personality of Godhead, Hari; vaira-anubandha-kṛt — determined to continue such enmity.
Translation: 
Śukadeva Gosvāmī said: Deliberating in this way, Kaṁsa, although determined to continue in enmity toward the Supreme Personality of Godhead, refrained from the vicious killing of his sister. He decided to wait until the Lord was born and then do what was needed.