And [Ibrahim's (Abraham)] invoking (of Allah) for his father's forgiveness was only because of a promise he [Ibrahim (Abraham)] had made to him (his father). But when it became clear to him [Ibrahim (Abraham)] that he (his father) is an enemy to Allah, he dissociated himself from him. Verily Ibrahim (Abraham) was Al-Awwah (has fifteen different meanings but the correct one seems to be that he used to invoke Allah with humility, glorify Him and remember Him much), and was forbearing. (Tafsir Al-Qurtubi).