Christian missionaries are too excited about the narration from Sahih Bukhari that talks about Prophet Muhammad’s (PBUH) alleged suicide attempts and they go far in deriving conclusion from it, thanks to their speculative reasoning faculty!
Let us analyze the narration and see how far the claim is true scrutinizing the point according to the rules of narration.

The Hadith:

The hadith from Sahih Bukhari is a long one its relevant part goes as;

‘…then after a few days Waraqa died and the Divine Inspiration was also paused for a while and the Prophet became so sad as we have heard that he intended several times to throw himself from the tops of high mountains and every time he went up the top of a mountain in order to throw himself down, Gabriel would appear before him and say, "O Muhammad! You are indeed Allah's Messenger in truth" whereupon his heart would become quiet and he would calm down and would return home …“ (Sahih Bukhari, Kitabul Ta’beer, Hadith 6467)

On the words about suicide:

The full Hadith of which above quoted is only a small part is indeed authentic. The Hadith has its unbroken chain of trustworthy narrators. But the words about suicide are not narrated through the chain rather they are added by Zuhri who is one of the narrators.

We clearly see the words;
‘As we have heard’

And this testifies that the words to follow are not reported through the chain mentioned in the beginning and thus for us they are nothing more than mere ‘hearsay’.

Hafiz Ibn Hajr writes;

“The one who says ‘as we have heard’ (fi ma balaghana) is Al-Zahri. And this means the sentence that has reached us [as if] from the reports about the Prophet, on whom be the peace and blessings of Allah, in this narration is from amongst the un-attributive reports of Zuhri and is not fully linked.” (Fath Al-Bari 19/449, Kitabul Ta’beer)

The words are doubtful:

The narration which is not fully linked and especially the un-attributive chains of Al-Zuhri have been considered untrustworthy by the Master of Hadith Sciences (Muhaddithin).

Knowing fully that being ignorant of the subtleties of the Islamic science of narration the non-Muslim readers will find it difficult to agree with the opinions of the Muslim scholars doubting such narration, I quote an orientalist.

Alfred Guilluame, the well known English Arabist writes;

“A word that very frequently precedes a statement is za’ama or za’amu, ‘he (they) alleged’. It carries with it more than a hint that the statement may not be true, though on the other hand it may be sound… Another indication of reserve if not skepticism underlies the expression fi ma dhukira li, as in the story of the jinn who listened to Muhammad as he prayed…An expression of similar import is fi ma balaghani.” (The Life of Muhammad: A translation of Ishaq’s Sirat Rasul Allah with introduction and notes by A. Guilluame Oxford University Press, Karachi, Seventeenth impression, 2004, p. xix)

Thus we find that even a Christian is agreeing that words transmitted using the expression ‘fi ma balaghana’ are doubtful.

This is even supported by the fact that the same report is found in elsewhere in Sahih Bukhari itself (Hadith 3) Sahih Muslim (Hadith 231), Mustadrik Al-Hakim (Hadith 4830), Baihaqi’s Dala’il Al-Nubuwwah (Hadith 445), Musnad Ahmad (Hadith 24681) and also as Ibn Hajr says in the works of Abu Nai’m, Isma’ili and Ibn Mardwiya and not one of them contains the words about alleged suicide attempts.

The reality that the words have reached us in an un-attributive way from a person who never met the Holy Prophet (PBUH) and the fact that so many other narrations, most of them through the same person -Al-Zuhri, do not make any mention of this leave us to safely conclude that there is no authentic report about the alleged suicide attempts. Therefore we find the attempts of the missionaries frustrated once again and all praise be to Allah!

Summary:

1- The narration from Sahih Bukhari from which the issue comes is actually authentic like other Ahadith from this mostly widely acclaimed collection but the words about the alleged suicide attempts are not of the same level but are rather doubtful.

2- Not only does a great classical Muslim scholar but even a Western orientalist testifies that the words reported using the expression ‘fi ma balaghani’ are indeed doubtful. So Christians cannot actually speculate and question Muslim way of employing their methodology.

3- The same incident is reported in many other works and not one of them mentions these doubtful words, thus leaving us to conclude that the words are indeed not reliable.

Conclusion:

The idea of Prophet’s (PBUH) alleged suicide attempts is not based on any reliable report and Christians ought to give up futile attempts of attacking the person of Holy Prophet (PBUH). Instead judging by the criteria by their own ‘lord god’ Jesus Christ (PBUH), ‘know them by their fruits’, they should study Islam and, insha’Allah, follow the Only True Religion of Allah!

INDEED ALLAH KNOWS THE BEST!