(ض) رَابَ يَرِيْبُ رَيْبًاrāba yarību rayban: to cast someone into doubt, to raise misgivings.
رَيْبٌrayb: doubt, suspicion (it is a verbal noun, maṣdar, but is also used as a noun, ism dhāt). ﴿ذٰلِكَ الْكِتٰبُ لَا رَيْبَ فِيْهِ﴾ (Al-Baqarah 2:2)
رِيْبَةٌrībah: doubt, suspicion, misgiving. ﴿لَا يَزَالُ بُنْيَانُهُمُ الَّذِيْ بَنَوْا رِيْبَةً فِيْ قُلُوْبِهِمْ﴾ (At-Tawbah 9:110)
Form IV (ifʿāl) اَرَابَ يُرِيْبُ اِرَابَةًarāba yurību irābatan: to cast into doubt; مُرِيْبٌmurīb (active participle, ism fāʿil): one who casts into doubt, who raises misgivings. ﴿وَاِنَّهُمْ لَفِيْ شَكٍّ مِّنْهُ مُرِيْبٍ﴾ (Hūd 11:110)
Form VIII (iftiʿāl) اِرْتَابَ يَرْتَابُ اِرْتِيَابًاirtāba yartābu irtiyāban: to doubt, to fall into suspicion; مُرْتَابٌmurtāb (active participle, ism fāʿil): one who doubts. ﴿اِذًا لَّارْتَابَ الْمُبْطِلُوْنَ﴾ (Al-ʿAnkabūt 29:48); ﴿مَنْ هُوَ مُسْرِفٌ مُّرْتَابٌ﴾ (Ghāfir 40:34)