Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: Wherever in the Qur'an the word qatl comes with a doubled letter (tashdid), it means punishment, and wherever it comes without the doubling, it means mercy.
Al-Tabarani recorded it. Its chain contains a narrator, Sahl bin Ibrahim al-Marwazi, whom I do not know.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التفسير / 10972
Hadith Gradingمحدثین:إسنادہ ضعیف
Hadith Takhrij«اخرجه الطبراني فى المعجم الكبير (1175)»