user-1: I'm aware of a story in the Pali Canon where a monk commited suicide by slitting his throat and achieved arahantship at the moment of death. 
Where in the texts can i find this story?
Thank you for your time.

user8044: I think that you are referring to Arahant Sappadāsa. You can find the verse of that great Arahant in http://mahamevnawa.ca/images/BookThumb/VoiceofEnlightenedMonksTheragathaSample.pdf

Those Who Walked the Path to Nibbana - Verses of Great Arahants 
This stanza was told by Arahant Sappadāsa
It has been 25 years since I received ordination. Yet, I have not achieved a mind fully concentrated, not even for a single moment.
I greatly suffered from sensual desires that arose in my mind. My mind was never tranquil. At the end, I was so discouraged and overcome with sorrow. With a sense of un-accomplishment, I went from one monastery to another.
I was determined to take my own life, even if I had to use a weapon on myself. What purpose is there in this life? How can a person like me, who received ordination because of my unshakable confidence in the Noble Triple Gem, disrobe? How can I leave this noble life and die as a householder?
And so, I took the knife on to my hand, and sat on my bed. So determined to cut off my veins, I placed the knife on my neck
Through that itself, ‘wise consideration’ arose in my mind. The suffering that arises from all defilements became apparent to me. I felt a sense of detachment through the understanding of that reality.
Through that understanding, my mind became free from all impurities. Look at the miracle of this noble Dhamma. I too attained the noble Triple knowledge. I fully accomplished the highest level of achievement one can achieve in the Supreme Buddha’s dispensation.


user7141: I am sorry i do not remember the names in this.But here is the complete story.
There was an ambitious monk while Buddha was alive.He wanted to reach nirvana but he had a little problem.He was able to reach "Samadhi" but couldn't hold on to it.he kept loosing and regaining it.He was terrified by the idea of facing his death without a "Samadhi" at least.He kept trying but it was obvious that nothing is going to change.One day he had enough of this game that his fate was having with him and decided to end his life while remaining in "Samadhi".This is not something Lord Buddha would agree with so no one knew this.he took a knife and cut his throat but years of practice was able to be useful at this moment.His mind started to reach higher levels of concentration and he went with that using his samadhi. By the time he was dead he was no longer a normal  monk he was an "Arahant".Lord Buddha heard the news and came to see his body and said this is not a normal one he is an "Arahant",Give the body the respect it deserves.That's how the rest of the people got to know about the real story.

user254: There might be something along those lines in SN 4.23 Godhika Sutta.
Page 85 of The Patimokkha Rules
Translated & Explained says,

Case (b) is apparently derived from SN 4.23, where Ven.
  Godhika takes his life and gains arahantship just moments before death


-1: <p>I'm aware of a story in the Pali Canon where a monk commited suicide by slitting his throat and achieved arahantship at the moment of death. </p>

<p>Where in the texts can i find this story?</p>

<p>Thank you for your time.</p>
 8044: <p>I think that you are referring to Arahant Sappadāsa. You can find the verse of that great Arahant in <a href="http://mahamevnawa.ca/images/BookThumb/VoiceofEnlightenedMonksTheragathaSample.pdf" rel="nofollow">http://mahamevnawa.ca/images/BookThumb/VoiceofEnlightenedMonksTheragathaSample.pdf</a></p>

<blockquote>
  <p><strong>Those Who Walked the Path to Nibbana - Verses of Great Arahants</strong> </p>
  
  <p><strong>This stanza was told by Arahant Sappadāsa</strong></p>
  
  <p>It has been 25 years since I received ordination. Yet, I have not achieved a mind fully concentrated, not even for a single moment.</p>
  
  <p>I greatly suffered from sensual desires that arose in my mind. My mind was never tranquil. At the end, I was so discouraged and overcome with sorrow. With a sense of un-accomplishment, I went from one monastery to another.</p>
  
  <p>I was determined to take my own life, even if I had to use a weapon on myself. What purpose is there in this life? How can a person like me, who received ordination because of my unshakable confidence in the Noble Triple Gem, disrobe? How can I leave this noble life and die as a householder?</p>
  
  <p>And so, I took the knife on to my hand, and sat on my bed. So determined to cut off my veins, I placed the knife on my neck</p>
  
  <p>Through that itself, ‘wise consideration’ arose in my mind. The suffering that arises from all defilements became apparent to me. I felt a sense of detachment through the understanding of that reality.</p>
  
  <p>Through that understanding, my mind became free from all impurities. Look at the miracle of this noble Dhamma. I too attained the noble Triple knowledge. I fully accomplished the highest level of achievement one can achieve in the Supreme Buddha’s dispensation.</p>
</blockquote>
 7141: <p>I am sorry i do not remember the names in this.But here is the complete story.</p>

<p>There was an ambitious monk while Buddha was alive.He wanted to reach nirvana but he had a little problem.He was able to reach "Samadhi" but couldn't hold on to it.he kept loosing and regaining it.He was terrified by the idea of facing his death without a "Samadhi" at least.He kept trying but it was obvious that nothing is going to change.One day he had enough of this game that his fate was having with him and decided to end his life while remaining in "Samadhi".This is not something Lord Buddha would agree with so no one knew this.he took a knife and cut his throat but years of practice was able to be useful at this moment.His mind started to reach higher levels of concentration and he went with that using his samadhi. By the time he was dead he was no longer a normal  monk he was an "Arahant".Lord Buddha heard the news and came to see his body and said this is not a normal one he is an "Arahant",Give the body the respect it deserves.That's how the rest of the people got to know about the real story.</p>
 254: <p>There might be something along those lines in SN 4.23 <a href="https://suttacentral.net/en/sn4.23">Godhika Sutta</a>.</p>

<p>Page 85 of <a href="http://www.accesstoinsight.org/lib/authors/thanissaro/bmc1.pdf">The Patimokkha Rules
Translated &amp; Explained</a> says,</p>

<blockquote>
  <p>Case (b) is apparently derived from SN 4.23, where Ven.
  Godhika takes his life and gains arahantship just moments before death</p>
</blockquote>
