Renewal of Wudū’ for every prayer.
It is Sunnah to renew Wudū’ for every prayer. If a Muslim has made Wudū’ for Maghrib prayer and is still maintaining his state if Wudū’ when ‘Ishā’ time comes in, it is Sunnah to perform Wudū’ again at ‘Ishā’ time.
This is proven by the following Hadeeth:
“The Prophet (PBUH) used to make Wudū’ for every prayer.”
(Al-Bukhāriy no. 214)
It is also Sunnah for a Muslim to maintain his state of Wudū’ during the day.
Thawbān (PBUH) said that the Prophet (PBUH) said,
“No one maintains his state of Wudū’ except a believer.”
(Ahmad no. 22434, Ibn Mājah no. 277, and Ad-Dārimiy no. 655)