Chapter IV Sloka 42

tSmad}ans<-Ut< TSw< }anaisnaTmn>,
iDvEn< s<zy< yaegmaitaei -art.

` tTsidit Imd -gvItasUpin;Tsu 
iv*aya< yaegzae Ik:[ajuRns<vade 
}ankmRs<Nyasyaegae nam ctuwaeR=Xyay>.

tasmdajnasambhta 
htstha jnsintmana | 
chittvaina saaya yogam
tihottiha bhrata  ( 4|42)||

om tatsaditi rmad bhagavadgtspaniatsu
brahmavidyy yogastre rkrjunasavde
jnakarmasannysayogo nma caturtho'dhyya

Therefore, with the sword of the knowledge (of the Self),
cut asunder the doubt of the self
born of ignorance and residing in thy heart,
and take refuge in Yoga. Arise, O Arjuna.

Commentary: Doubt causes a great deal of mental torment. It is most sinful. It is born of ignorance. Kill it ruthlessly with the knowledge of the Self. Now stand up and fight, O Arjuna.
(This chapter is known by the names: Jnana Yoga, Abhyasa Yoga and Jnana-karma-sannyasa Yoga also.)
Thus in the Upanishads of the glorious Bhagavad Gita, the science of the Eternal, the scripture of Yoga, the dialogue between Sri Krishna and Arjuna, ends the fourth discourse entitled:
"The Yoga of Renunciation of Action in Knowledge."