First of all, it should be clear that purification is a prerequisite for the validity of Prayer. Accordingly, one should be careful about the purity of his body, clothes, and the place in which one prays. If one of these three items is not pure, one’s Prayer will be null and void. By the same token, the validity of Wudu’ should be given due care, for it prepares the body and the soul for Prayer.
Muslim scholars say that though talk doesn’t nullify Wudu’, it’s detested except for making Dhikr or when needed such as responding to Salam greetings, etc.
Sheikh `Atiyyah Saqr, former head of Al-Azhar Fatwa Committee, states: “In principle, talk during Wudu’ doesn’t nullify it, but it’s detested. A Muslim is recommended to concentrate on perfecting his Wudu’, and not to talk except for Dhikr and goodness.”
The prominent Muslim scholar, Sheikh Ibrahim Gulhum, the Imam in the Egyptian Endowments Ministry, adds: “According to the Maliki and Hanafi schools of Fiqh, talking during Wudu’ is not recommended for a Muslim except to make Dhikr or meet a need.
Wudu’, in fact, is a prerequisite for the validity of some acts worship such as Prayer and circumambulation round the Ka`bah. So, a Muslim should preoccupy his mind with fulfilling its requirements so as to prepare himself to stand before Allah in humbleness and consciousness.
Therefore, I advise you, dear Muslim brother/sister, not to engage your mind in idle talk during Wudu’. Rather, you are recommended to let it focus on making Dhikr. In this context, Abu Musa Al-Ash`ari, may Allah be pleased with him, said: “I brought water to the Messenger of Allah, peace and blessings be upon him, to make Wudu’. Then, I heard him say, ‘O Allah! Forgive my sin, may my house spacious, and bless my provision.’ I asked him, ‘O Prophet of Allah! I heard you pray Allah saying such-and-such.’ ‘Does this prayer leave anything (of good)!’ he replied.” An-Nasa’I stated this Hadith under the heading “What a Worshipper Says after Wudu’”, while ibn As-Sunni stated it under the heading “What a Worshiper Says During Wudu’”. Imam An-Nawawi said: The two views are passable.”

However, in his well-known book, Fiqh As-Sunnah, Sheikh Sayyed Sabiq holds a contrary view:
“It is permissible to speak while performing Wudu’. There is nothing reported from the Sunnah that prohibits it.”
Based on the above facts, it becomes crystal clear that talk during Wudu’ doesn’t render it invalid, though it’s detested except for Dhikr, responding to Salam, etc.