Praise be to Allah.
The basic principle is that one should raise the hands when making du’aa’, because the Prophet (peace and blessings of Allaah be upon him) said: “Allaah is Most Generous, and He dislikes to turn away empty the hands of His slave when he raises them to Him.” Narrated by al-Tirmidhi, 3556; classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.
It says in Tuhfat al-Ahwadhi:
This hadeeth indicates that it is mustahabb to raise the hands when making du’aa’. There are many ahaadeeth concerning that.
But it was narrated with regard to the khateeb on Fridays that when he makes du’aa’ on the minbar, he should point with his forefinger only and not raise his hands. Indeed some of the Sahaabah denounced the khateeb who raises his hands in du’aa’.
Muslim (874) and Abu Dawood (1104) narrated that ‘Umaarah ibn Ru’aybah saw Bishr ibn Marwaan on the minbar raising his hands (Abu Dawood added: when he was making du’aa’ on Friday), and he said: “May Allaah make these two hands ugly. I saw the Messenger of Allaah (peace and blessings of Allaah be upon him) doing no more than this with his hand,” and he gestured with his forefinger.
This indicates that the Sunnah is not to raise the hands during the khutbah, This is the view of Maalik and our companions and others.
In Tuhfat al-Ahwadhi it says:
This hadeeth indicates that it is makrooh to raise the hands on the minbar when making du’aa’.
As it is not prescribed for the khateeb to raise his hands, the members of the congregation are like him because they follow his lead.
But if the imam prays for rain on Friday whilst he is on the minbar, the Sunnah is to raise the hands, and for the members of the congregation to raise their hands and make du’aa’ with him.
Al-Bukhaari (933) and Muslim (897) narrated that Anas ibn Maalik said: The people were stricken with drought at the time of the Prophet (peace and blessings of Allaah be upon him), so whilst the Prophet (peace and blessings of Allaah be upon him) was delivering the khutbah one Friday, a Bedouin stood up and said, “O Messenger of Allaah, our wealth has been destroyed and our children are hungry, Pray to Allaah for us.” So he raised his hands [al-Bukhaari added in his muta’allaq report: and the people raised their hands with the Messenger of Allaah (peace and blessings of Allaah be upon him) making du’aa’], and we did not see any cloud in the sky. But by the One in Whose hand is my soul, hardly had he lowered (his hands) but there appeared clouds like mountains, and hardly had he come down from his minbar but I saw rain running down his beard (peace and blessings of Allaah be upon him). It rained that day, and the day after, and the day after, until the following Friday. Then that Bedouin or someone else stood up and said, “O Messenger of Allaah, our buildings have been destroyed and our wealth had been flooded. Pray to Allaah for us.” So he raised his hands and said, “O Allaah, around us and not on us.” Each time his hand pointed to part of the clouds they parted, and the clouds formed a ring around Madeenah. The wadis flowed with water for a month and no one came from any direction but he spoke of the heavy rain.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked:
What is the ruling on raising one's hands when the imam is delivering the khutbah on Friday? He replied:
Raising the hands when the imam is delivering the khutbah on Friday is not prescribed in sharee’ah. The Sahaabah denounced Bishr ibn Marwaan when he raised his hands during the Friday khutbah. But an exception is made in the case of prayers for rain (istisqaa’), because it is proven that the Prophet (peace and blessings of Allaah be upon him) raised his hands when praying to Allaah for rain during the Friday khutbah, and the people raised their hands with him. But apart from that one should not raise one's hands when making du’aa’ during the Friday khutbah.
Fataawa Arkaan al-Islam, p. 392.
And Allaah knows best.