Tafsir of Ad-Dukhan 44:20

"And indeed, I have sought refuge in my Lord and your Lord": That is, I have taken shelter in Him, the Exalted, and have relied upon Him, Glorified be His majesty.

"Lest you stone me": That is, lest you harm me through beating or verbal abuse, or lest you kill me. This has been narrated from Qatadah and a group of others. It is said that when he said, "Do not exalt yourselves against Allah," they threatened him with death, so he said this.

In al-Bahr, it is stated that this was before the Almighty informed him of their inability to stone him with His words, Glorified be He: "They will not reach you both." The sentence is a conjunction to the preceding independent clause. Abu 'Amr and the two brothers (Hamzah and al-Kisa'i) read it as 'attu (عُتَّ) by assimilating the dhal into the ta'.