IS militants in Raqqa - AP
The killing was reportedly carried out in the Syrian town of Raqqa
An Islamic State militant carried out a public "execution" of his mother because she asked him to leave the group, activists say.
Ali Saqr, 21, killed his mother, Lena al-Qasem, 45, outside the post office in Raqqa, Syria, eyewitnesses said.
Raqqa has served as IS' de facto capital since the group captured the city in August 2013.
IS does not tolerate any dissent and imposes brutal punishments, often carried out in public.
The UK-based monitoring group, the Syrian Observatory for Human Rights (SOHR) and the activist group "Raqqa is Being Slaughtered Silently" reported the incident.
Lena al-Qasem had reportedly told her son that the US-led military alliance fighting IS would "wipe out" the group, and tried to convince him to leave the city with her.
Her son is then said to have informed the group of her
comment, and they ordered her killing.
Ali Saqr is reported to have shot her outside the post office where she worked, in front of hundreds of people.
IS, a jihadist group which follows its own extreme version of Sunni Islam, took over large parts of Iraq and Syria in 2014.
Since then the group has killed more than 2,000 people for reasons including homosexuality, and for the alleged practice of magic and apostasy, according to the SOHR.