ya imam paramam guhyam madbhakteshvabhidhaasyati |
bhaktim mayi paraam kritvaa maamevaishyatyasamshayaha || 68 ||
na cha tasmaanmanushyeshu kaschinme priyakrittamaha |
bhavitaa na cha me tasmaadanyaha priyataro bhuvi || 69 ||

He who, having devotion to me, explains this supreme secret to my devotees, will reach me alone, no doubt. And compared to him, no one else among humans performs actions which are dear to me. Nor will there be anyone else on this earth dearer to me than him.
yaha : he who
imam : this
paramam : supreme
guhyam : secret
madbhakteshu : to my devotees
abhidhaasyati : explains
bhaktim : devotion
mayi : to me
paraam : supreme
kritvaa : having done
maam : me
eva : alone
eshyati : reach
asamshayaha : no doubt
na : no
cha : and
tasmaat : compared to him
manushyeshu : among humans
kaschit : else
me : me
priyakrittamaha : performing actions which are dear
bhavitaa : in the future
na : no
cha : and
tasmaat : to him
anyaha : anyone
priyataraha : dearer
bhuvi : on this earth
Previously, Shri Krishna described the tradition and method by which the Gita discourse should be handed down from the teacher to the student. He now describes the teacher who imparts this knowledge to society. He says that the foremost quality of the teacher is devotion to Ishvara, and only such a teacher can impart the real knowledge of the Gita to students, who are also devoted to Ishvara. The teacher should deliver the teaching in the spirit of karma yoga, in a spirit of service to Ishvara, not for name, fame or honour.
In return for their selfless service of teaching the Gita, Shri Krishna declares in no uncertain terms that the teacher will go to Ishvara, he will liberated from all sorrow. Praising the teacher, he says that there is no other person on this earth who does actions that are dearer than the action of teaching the Gita. He further says that the teacher becomes the dearest person Ishvara. It is a status so special that it spans the past, present and future. In other words, this special position transcends all time, such is its greatness.
Why does Ishvara love the teacher so much? The teacher assists Ishvara in the his mission to rid the world of ignorance. A teacher can assess the needs of the seeker, and give him the guidance from the Gita needed for that particular situation of the seeker. Only a qualified teacher is able to do that, as opposed to someone randomly reading shlokas from the Gita. Furthermore, very few people are able to teach the true meaning of the Gita, and convey to the student exactly what Ishvara wants to convey, without distorting anything.