Ismail Haniya, the Hamas leader in Gaza, said that the truce was in both sides' interests.
"The calm is going to bring stability to Israel if they commit themselves to it," he said. "The calm is going to ease the lives of Gazans."
But just hours before the ceasefire was due to come into effect Palestinian fighters had fired dozens of mortars and rockets into southern Israel, while an Israeli air raid in the north of Gaza injured two people.
The attacks on Wednesday seemed to reflect the lack of trust of that each side has in the other.
Ghazi Hamad, a senior Hamas official, told Al Jazeera that he was confident that Palestinian groups in the Gaza Strip would honour the deal but was not sure that Israel would stop its attacks.
"We cannot trust Israel because I think Israel is not interested in a truce or ceasefire ... but here in Gaza I think that all Palestinian factions are together, and I think of all of them expressed their respect and that they want to be committed to the ceasefire," he said.
For his part, Mark Regev, the Israeli government spokesman, questioned whether Hamas would respect the ceasefire.
"We have to see that this isn't a calm that is used by the terrorist in Gaza as a timeout, that they just use this to rearm and group," he told Al Jazeera.
"I think everyone is looking at Hamas, are they really serious about this?" he asked. "Their track record is one of continued violence, terrorism and murder."
Meir Sheetrit, an Israeli cabinet minister, criticised the deal, saying it was "a great accomplishment for Hamas".
"They prove that their determination and the war and the continued attacks on Israel help them achieve what they want," he said.
If the ceasefire deal lasts for three days, Israel will ease its blockade on Gaza, allowing vital supplies into the territory.