This verse from Rigved Book 4, Hymn 18 alludes to Indra killing his own father!
4.18.12. Who was he then who made thy Mother widow? Who sought to stay thee lying still or moving? What God, when by the foot thy Sire thou tookest and slewest, was at hand to give thee comfort?
कस्ते॑ मा॒तरं॑ वि॒धवा॑मचक्रच्छ॒युं कस्त्वाम॑जिघांस॒च्चर॑न्तम्।
कस्ते॑ दे॒वो अधि॑ मार्डी॒क आ॑सी॒द्यत्प्राक्षि॑णाः पि॒तरं॑ पाद॒गृह्य॑॥ ४.०१८.१२
Another verse from RV Book 6, Hymn 59 says:
- I WILL declare, while juices flow, the manly deeds that ye have done: Your Fathers, enemies of Gods, were smitten down, and, Indra-Agni, ye survive.
प्र नु वो॑चा सु॒तेषु॑ वां वी॒र्या॒३ यानि॑ च॒क्रथु॑।
ह॒तासो॑ वां पि॒तरो॑ दे॒वश॑त्रव॒ इन्द्रा॑ग्नी॒ जीव॑थो यु॒वम्॥ ६.०५९.०१
Is there any Puranic story that describes this more in detail? Also who could this father have been since Kashyap has been mentioned as being alive even in later times? Could it be Dyaus as mentioned in this answer?