samatha after vipassana Can one correctly practice anapanasati when one is very used to Mahasi vipassana? 


How? Why?


  Can one correctly practice vipassana when one is very used to anapanasati or any other samatha practice? 


How? Why?


  A person who is used to vipassana is supposed to turn off the habit of seeing things as they are? Can vipassana be useful during anapanasati or would it be more of a distraction to onepointed consentration?


How? Why?
OP: Simultaneous vipassana &amp; samatha - in this version of the question


(Yuga,naddha) Paṭipadā Sutta mention there are 4 types of practitioners:


  (1) “insight preceded by calm” - samatha,pubb’angama vipassanā
  
  (2) “calm preceded by insight” - vipassana,pubb’angama samatha
  
  (3) “calm coupled with insight” - samatha,vipassana,yuga.naddha
  
  (4) “a mind seized by dharma-restlessness” - dhamm’uddhacca,viggahita manasa


Practising Samatha and Vipassana together is: 


  (3) “calm coupled with insight” - samatha,vipassana,yuga.naddha


Regardless of which practice you start with, both Samatha and Vipassana is needed to reach the ultimate goal:



(Mūla) Samatha Vipassanā Sutta

Also, it is best one allocate time for both:



Catu Kāla Sutta 1

Also, vipassana practises (body contemplation - breath meditation, posture, movement, body parts, elements, corpse) leads to Samadhi as per Kaya,gatā,sati Sutta:


  As he dwells thus diligent, exertive, resolute, his memories and thoughts of the household life are
  abandoned. With their abandoning, his mind steadies itself internally, settles, becomes one, attains samadhi [becomes concentrated].
  
  In this way, bhikshus, a monk cultivates mindfulness regarding the body.


Which intern leads to the 6 super knowledges:



Kaya,gatā,sati Sutta

Edit:


  OP: samatha after vipassana


This is:


  (1) “insight preceded by calm” - samatha,pubb’angama vipassanā


.


  OP: Can one correctly practice anapanasati when one is very used to vipassana?


Anapanasati is also a form of vipassana which takes you to the highest goal of Nibbana.



Source: Anapanasati


  Can one correctly practice vipassana when one is very used to anapanasati or any other samatha practice?


If you are skilled in Vipassana it is recommended to seek a Samatha teacher and practice Samatha:

 

Source: (Samatha Vipassanā) Samādhi Sutta 3

(Samādhi) Bala Sutta describes how one should develop skills in Samatha:




  OP: A person who is used to vipassana is supposed to turn off the habit of seeing things as they are?


No, not necessarily:


  Even this first dhyana is (mentally) constructed [mind-made], intentionally formed.
  
  What is
  constructed and intentionally formed is impermanent, subject to ending.
  
  If he is steady therein, he attains the destruction of the mental influxes.


Similarly in other Jhanas as given in Aṭṭhaka,nāgara Sutta

Here one sees the true nature of things while doing Samatha/Samadhi.

Also, Saṅkhitta Dhamma Sutta discusses the teachings in concise form, mentions the practice of mindfulness with Jhana ultimately resulting in full enlightenment:


  When, bhikshu, this samadhi has been cultivated, well cultivated by you, then you should train yourself thus:
  
  “I will dwell exertive, clearly aware, mindful,
  
  observing [contemplating] [body | feeling | mind | dhamma] the in the [body | feeling | mind | dhamma],
  
  removing covetousness and displeasure [discontent] in regard to the world.”
  
  Thus, bhikshu, you should train yourself.
  
  When, bhikshu, this samadhi has been cultivated, well cultivated by you, then, you, bhikshu,
  
  THE 1 ST DHYANA:
  
  should cultivate this samadhi with initial application, with sustained application;
  
  should cultivate this samadhi without initial application, with only sustained application;
  
  THE 2 ND DHYANA:
  
  should cultivate this samadhi without initial application, without sustained application;
  
  should cultivate this samadhi with zest;
  
  THE 3RD DHYANA:
  
  should cultivate this samadhi zest-free;
  
  should cultivate this samadhi attended by comfort;
  
  THE 4 TH DHYANA:
  
  should cultivate this samadhi attended by equanimity.


Saṅkhitta Dhamma Sutta


  OP: Can vipassana be useful during anapanasati or would it be more of a distraction to onepointed consentration?


Each triad corresponds to a Satipattana, which is Vipassana.

The last triad of Anapanasathis is explicitly to see things as they are which is vipassana:



Source: Ānâpāna,sati Sutta

Essentially one is doing Vipassana when one is doing Anapanasati.



The need of Samadhi in tandem is evident from the following Suttas.

Also, a meditation how can attain and also have a theoretical understanding of Samadhi is the foremost meditator:

 

Samādhi Samāpatti Sutta. Similar one who understands Samadhi can remain in Samadhi is the foremost:



Samādhi Mūlaka Ṭhiti Sutta

Similarly, one who understands and skilful in emerging from Samadhi is the foremost meditator. - Samādhi Mūlaka Vuṭṭhāna Sutta

Similarly, one who understands samadhi and is fitfor Samadhi is the foremost meditator. - Samādhi Mūlaka Kallita Sutta

Similarly, one who is understands samadhi and is skilled in the concentration object is the foremost meditator. - Samādhi Mūlaka Ārammaṇa Sutta

Similarly, one who understands and resorts to samadhi is the foremost meditator. - Samādhi Mūlaka Go,cara Sutta

Similarly, one who understands and has resolution in samadhi is the foremost meditator. - Samādhi Mūlaka Abhinīhāra Sutta

Similarly, one who understands and care about samadhi is the foremost meditator. - Samādhi Mūlaka Sakkacca,kārī Sutta

Similarly, one understands and is committed to samadhi is the foremost meditator. - Samādhi Mūlaka Sātacca,kārī Sutta

Similarly, one who understands and is skilled in what is suitable regarding samadhi is the foremost meditator. - Samādhi Mūlaka Sappāya,kārī Sutta

Following skills: 



Himavanta Sutta. Also Vasa Suttā which includes theoretical knowledge.

And the following masteries are useful: