[Why Is Mindfulness Of Buddha The Foremost Skilful Means?]
[The] Dharma Door [of] mindfulness [of] Buddha, [is] easy [to] start, yet [with its] success great, [with] little physical exertion, yet attaining results swiftly.
[Be it] walking, standing, sitting [or] lying down, [at] all times [and] all places, all [are] good [for] recitation.
[When To Have Verbal And Silent Recitation?]
If dressing [is] orderly, [with] hands [and] face clean, verbal recitation [and] silent recitation [are] all alright.
If  lying down, and  dressing [is] not orderly,  not yet washing [the] face [and] rinsing [the mouth], and  at unclean places, or  when [with] major [or] minor [restroom] relief, all must [be with] silent recitation, [as these occasions are] not suitable [for it to be] verbal.
[Note: In the Master’s ‘Fourth Reply Letter To Layperson Gāo Shàolín’ (复高邵麟居士书四), he also taught that, ‘When lying [down, it is] only suitable [to have] silent recitation. [There] must not [be] verbal [recitation]. If [with] verbal [recitation], first, thus [is it] not respectful, second thus [is it] harmful [for] breathing [and vitality].’ (卧时只宜默念，不可出声。若出声，一则不恭，二则伤气 [i.e. 损伤元气]。) Thus, especially the weak and bedridden, should recite verbally when propped up or seated upright, with more focus on silent recitation, when lying down.]
Although lying down [or sleeping, there] must not [be] nudity [of the] body. [There] must [be] wearing [of] shirt [and] pants. [There] must not [be] non-restraint.
[How To Gather The Six Roots For Pure Mindfulness In Continual Succession?]
Desiring [to] gather [in the mind, away from] false [or stray] thoughts, first, [the] mind must remain reverent constantly, [as] if before [the] Buddha, not daring [to] give rise [to] other kinds [of] thoughts.
Second, [there] must [be] word [by] word, line [by] line, [the] mind within reciting clearly, [the] mouth within reciting clearly. Thus [will] false thoughts naturally [and] gradually disappear.
Even if [with] silent recitation, [there] also must [be] listening.
With [the] mind together reciting, [it] then has sound.
[With your] own ears, listening [to] one’s sound within [the] mind, [it should] still [be] clearly [heard].
[In the] Śūraṅgama Sūtra, Great Power Arrived Bodhisattva said, ‘Gathering in [the] six roots, [with] pure mindfulness [in] continual succession, [to] attain Sānmódì [i.e. Samādhi], this [is] as [the] foremost’. [This is with] emphasis on listening.
[The] ‘six roots’, are [the] eyes, ears, nose, tongue, body [and] mind.
The mind, is [the] mind root. [The] mouth, is [the] tongue root, [though used for reciting and not tasting here]. Listening, is [of the] ear root.
[With the] mind mindful, [the] mouth reciting, [and the] ears listening, these three roots [are as] one gathered, [with the] eyes also not seeing [the] East [and] looking [at the] West, [the] nose also not smelling other smells, [the] body also not daring [to be] unrestrained, pleasure-seeking [and] slack, [this is] thus named [as] ‘gathering in [the] six roots’.
‘Gathering in [the] six roots’, and reciting, naturally without defiled, mixed [and] false thoughts, [is] thus named [as] ‘pure mindfulness’.
「 净念」，必须要常常相继不断，故名「 净念相继」。
‘Pure mindfulness’, must have constantly continual succession without interruption, thus named [as] ‘pure mindfulness [in] continual succession.’
[If] able [to have] ‘pure mindfulness [in] continual succession’, as time passes [by], thus attaining Samādhi [From] Mindfulness [Of] Buddha.
This ‘gathering in [the] six roots, [with] pure mindfulness [in] continual succession’, [is] for attaining of Samādhi’s ‘foremost’ wonderful method.
Thus said, ‘[to] attain Sānmódì, this [is] as [the] foremost.’
‘Sānmódì’, is Samādhi other name.
Thus mindful of, [there will] definitely be pure thoughts always there, [and] one day, [you will] completely [be] without [any] false thoughts.
Pure Land Tradition’s 13th Patriarch Great Master Yìnguāng
Letter To [Dharma Masters (And/Or)] Teacher[s] Cultivating [The] Pure Land [Path]
Section On Mahāsthāmaprāpta Bodhisattva’s Perfect Penetration With Mindfulness Of Buddha
Can Buddhists Chant In Restrooms & Bedrooms?
Namo Amituofo : Translation and note by Shen Shi’an