Is it permissible for a traveler who combines prayers to separate the two prayers with a time for ablution, or must he follow them with a single ablution?

"The excused person suffices with one ablution (wudu') after the time for prayer begins, to pray with it as many obligatory and supererogatory prayers as he wishes, and to combine two prayers with it. This is the ruling (fatwa) adopted by us and is the madhhab of the Hanbalis. As for sequential performance (muwalat) between combined prayers: if the combining is done by advancing the second prayer (jama' taqdim), it is a condition according to the majority of scholars. However, if the combining is done by delaying the first prayer (jama' ta'khir), sequential performance is not a condition according to the majority of scholars."