1. What to Say Before Ablution
The Messenger of Allaah (صلي الله عليه و سلم) said: “There is no Salaat for him who has no ablution (Wudu), and there is no ablution for him who has not mentioned the name of Allaah upon it”.
“In the name of Allaah”
[Reference: Saheeh al-Jaami’ as-Sagheer wa Ziyaadatih]
2. What to Say After Ablution
The Messenger of Allaah (صلي الله عليه و سلم) said: “There is not one of you that makes Wudu and performs the rites of Wudu, then says when he has completed his Wudu:
أَشْهَدُ أَنْ لَا إِلَهَ إلَّا اللهُ
لَا شَرِيكَ لَهُ،
أَنَّ مُحَمَّداً عَبْدُهُ وَرَسُولُهُ.
“I bear witness that none has the right to be worshipped but Allaah alone, Who has no partner; and that Muhammad is His slave and His Messenger”
Except that the eight gates of Paradise would open up for him, that he may enter from whichever he would please.”
[Reference: Saheeh Muslim]