Bishr bin Qays narrates from Sayyiduna Umar bin al-Khattab (may Allah be pleased with him): Once in Ramadan I was with Sayyiduna Umar (may Allah be pleased with him) in the evening, and it was a cloudy day. He thought that the sun had set, so Sayyiduna Umar (may Allah be pleased with him) drank and gave me to drink too. Then they saw it on the slope of the mountain, and Sayyiduna Umar (may Allah be pleased with him) said: "It does not matter; we will fast a day in its place."
The agreement of these narrations from Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) on making up the fast is evidence that the narration of Zayd bin Wahb about not making it up is mistaken.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8015