What is the ruling on the 'Isha prayer if the worshiper performed ablution with the intention of renewing it, then it became clear to him that he had invalidated his ablution before performing ablution for renewal?

Scholars differ concerning one who performs ablution (wudu) with the intention of renewing purity, having forgotten his ritual impurity (hadath), then remembers that he was indeed impure. Is his purification valid or not? There are two opinions:

The first opinion: His purification is not valid, because he did not intend to remove the ritual impurity, or his intention was indecisive.

The second opinion: His purification is valid, because it is a prescribed purification that coincided with a state of ritual impurity, thereby removing it. This is the more apparent view and is the madhhab of the Hanbalis. Sheikh Ibn Uthaymeen and Sheikh Khalid Al-Musayqih chose this opinion, on the condition that he was genuinely forgetful of his impurity, not merely recalling it.

The cautious approach, to avoid dispute, is to repeat the ablution and the prayer.