Yes, this is a true story and actually it happened but with some difference in details.
- Abu Obaida Ibn Al-Jarrah (may Allah be pleased with him).
- Khalifah Omar Ibn Al-Khattab (may Allah be pleased with him).
Place and Time
Year: 17th Hijri, 638 AD.
Place: The Levant (Syria, Lebanon, Jordan, and Palestine).
The Muslim armies led by Abu Obaida have been conquering The Levant and making quick and continuous victories, and Romans were retreating. But simultaneously Muslim armies led by Sa'd bin Abu Waqqas were going to battle the Persians. The persian chosroes prepared more than 200 thousand warriors for that battle, while the Muslims were only 32000, there was big imbalance (yet Muslims won that battle later, and it's called Qadisya معركة القادسية).
Khalife Omar Ibn Al-Khattab worried that Muslims would lose the battle against the perisans and then the Muslim armies across The Levant and the Arabian peninsula would be at a great danger, so he sent a message to Abu Obaida ordering him to retreat and regroup his forces. And so Abu Obaida did, he grouped in Homs, and Khalid bin A-Walid (who led a part of the army) grouped in Damascus.
But when the Romans saw that, they prepared a huge army to re-control the Levant, Abu Obaida realized that Muslims may not be able to defend the cities they conquered, and so he decided to retreat to the borderlines of the Arabian peninsula (there are more details here about how they agreed on that).
Before leaving Homs, Abu Obaida ordered the Jiziah keeper Habib bin Muslimah to give back the Jiziah money to those who it's been taken from (in Homs and every city they're leaving), as Muslims no longer are able to protect them, and Jiziah is a "price" for protection. Abu Obaidah said to them:
نحن على ما كان بيننا وبينكم من الصلح لا نرجع عنه إلا أن ترجعوا
We keep the oath between you and us, and won't break it unless you do.
The people in Homs were greatly surprised and pleased with that, they said:
ردكم الله إلينا ولعن الله الذين كانوا يملوكننا من الروم لكنهم والله لو
كانوا هم ما ردوا علينا بل غصبونا وأخذوا مع هذا ما قدروا عليه من
May Allah return you to us and damn the Romans who were ruling us. We
swear they wouldn't return our money to us if they were you, but they
would harrow us and take additionally what they can from us.
Abu Obaida also sent a messenger to Khalifah Omar telling him the plans and situation, and asking him for reinforcements (later Omar himself came with reinforcements). And the Muslim armies then retreated to the borderlines.
People of the left cities agreed that they don't want to allow Romans to reenter and control it again, they agreed that they will close the doors and hold their cities until the battle between Muslims and Romans is over, if the Romans win, they will surrender let them re-control it, if the Muslims win, then they will be happy for their return, as the oath between them and Muslims still stand. (However, this part is not mentioned in the references I give below, I've read it in a reference while researching this story, and lost the link to that reference).
Of course, Muslims won the battle of Qadisya, and reinforcements of Omar were about to reach the Muslim armies led by Abu Obaida, the Roman allies from above Euphrates river feared and returned home leaving the Romans alone.