Master Honen abandoned up all religious practices and followed the single path of the Nembutsu. In Volume Two of the Wago Toroku (A Record of the Light) is the following:

Question: Will all who recite the Nembutsu be born in the Pure Land?
Answer: Those who recite the Nembutsu with “Buddha-centered power” will but those who do so with “self-centered effort” absolutely will not.

As can be determined by the above, Master Honen also made a distinction between reciting the Nembutsu with “self-centered effort” and with “Buddha-centered power.”

Further, in the document that is said to be the last that Master Honen wrote before leaving this world, the Ichimai Kishomon (The One Page Document), it states:

I believe there is no way to be born in the Pure Land of Ultimate Joy other than by reciting Namo Amida Butsu without doubt. You can speak about the “three minds” and the “four practices,” but these things are contained within faith in Namo Amida Butsu. Wanting to know more about this goes against the compassion of the two sacred beings (Shakyamuni Buddha and Amida Buddha) and is not within the spirit of the Primal Vow.

From this, it appears that the Venerable Master also considered shinjin while reciting the Nembutsu to be important. In Shui Gotoroku (Sacred Words, Picked and Collected), however, is the passage:

In the “three minds” there are the “wisdom of the three minds” (sanshin no chigu) and the “practice of the three minds” (sanshin no gyo-gu) ... The reason we single-heartedly recite the Nembutsu and are born in the Pure Land without doubt is because of this “practice of the three minds.”

Further, in the Saiho Shinan-sho (Notes that Guide towards the West), it states:

Recite the myogo single-mindedly with faith in the commentary on the phrase, “That Buddha is presently becoming a Buddha.” When you recite the myogo, the three minds automatically accompany the recitation.

(The phrase, “That Buddha is presently becoming a Buddha,” seems to be a contradiction, but it points to the fact that a Buddha has lowered itself from the Absolutely Enlightened State in order to engage in the process of “saving” all sentient beings, after which it will revert to its Absolute Enlightened State.)