From the UAE Embassy in Washington:
The United Arab Emirates appreciates continued US efforts to reach a Palestine-Israel peace agreement. This plan is a serious initiative that addresses many issues raised over the years.
The only way to guarantee a lasting solution is to reach an agreement between all concerned parties. The UAE believes that Palestinians and Israelis can achieve lasting peace and genuine coexistence with the support of the international community. The plan announced today offers an important starting point for a return to negotiations within a US-led international framework.
Saudi Arabia tried to have it both ways. Here's what it says on its Ministry of Foreign Affairs page:
The Ministry of Foreign Affairs of The Kingdom of Saudi Arabia has viewed the U.S. Administration's announcement of its peace plan titled: "Vision for Peace, Prosperity, and a Brighter Future".
In light of the announcement, the Kingdom reiterates its support for all efforts aimed at reaching a just and comprehensive resolution to the Palestinian cause.
Since the time of the Founder King Abdulaziz bin Abdulrahman Al-Saud, and through the reign of the Custodian of the Two Holy Mosques, King Salman bin Abdulaziz Al-Saud, the Kingdom of Saudi Arabia has been at the forefront of the efforts in support of the brotherly Palestinian people, and in standing by their side in all international forums to attain their legitimate rights.
Among these efforts was the presentation of the Arab Peace Initiative in 2002, which stressed, in clear terms, that a military solution to the conflict has not brought peace or security to any party, and the comprehensive and just peace is a strategic option.
The kingdom appreciates the efforts of President Trump's Administration to develop a comprehensive peace plan between the Palestinian and the Israeli sides, and encourages the start of direct peace negotiations between the Palestinian and Israeli sides, under the auspices of the United States, and to resolve any disagreements with aspects of the plan through negotiations, in order to move forward the peace process to reach an agreement that achieves legitimate rights of the Palestinian people.
But Ma'an reports that the King of Saudi Arabia called up Mahmoud Abbas:
President Mahmoud Abbas received, on Tuesday evening, a phone call from the Custodian of the Two Holy Mosques, King Salman bin Abdulaziz Al Saud.
The King stressed to President Abbas that the kingdom's position will not change from the Palestinian issue in order to preserve the rights of the Palestinian people.
He said: "Your issue is ours, and the issue of Arabs and Muslims, and we are with you." He called for the necessity of achieving a comprehensive and just peace, considering that peace is a strategic choice, leading to a final solution that achieves the national rights of the Palestinian people.