Islamic Ruling on Raising the Finger After Wudu
The Islamic ruling is that making dua after wudu is recommended, but raising the index finger toward the sky has no proof and should be avoided.
According to a hadith narrated by Anas ibn Malik, the Prophet ﷺ said that whoever performs wudu and then recites the dua that includes the testimony of faith and asks Allah to make him among the repentant and the purified, the eight gates of Paradise are opened for him and he may enter from whichever he wishes.
Islamic scholars used this hadith to say that reciting this dua after wudu is recommended. Other duas mentioned in hadith may also be read after wudu. The scholars also mentioned that while making dua, raising both hands and facing the qiblah is recommended.
However, the scholars clearly stated that raising the index finger toward the sky while reciting this dua is not allowed because there is no evidence for it. Classical fiqh books mention that one should not raise one or both index fingers during this dua, and doing so was described as an action without proof.
Therefore, the fatwa from Islamic scholars is that after wudu, dua is recommended, hands may be raised like a normal supplication, but raising the index finger toward the sky should be avoided.