This Hadith is related to Hazrat Abu Hurairah (R.A.). He says that my intimate friend Hadhrat Muhammad (Sall-Allaho-'Alayhe-Wasallam) told me that:
“In this Ummah, the troops would be headed towards Sindh & Hind”
"Hazrat Abu Hurairah (R.A.) says that if I could find a chance to participate in any of such movement & (while participating in it) I be got martyred, then well & good; if came back as a survived warrior, then I would be a free Abu Hurairah, to whom Allah Almighty would have given freedom from the Hell.”

A few references:

With these words, only Imam bin Hambal (R) narrated this Hadith in ‘Masnad’ and Ibn-e-Kaseer copied with his reference in ‘Al-Badaya Wa Nahaya’.
Qazi Ahmad Shakir gave this Hadees the beautiful stability in the explanation & search of ‘Masnad Ahmad’.
Imam Nisai did narrate this Hadith in both his books: ‘As Sunan Al Mujtaba’ & ‘As Sunan Al Kubra’ with the following wordings, that Hazrat Abu Hurairah (R.A.) says, Hadhrat Muhammad (Sall-Allaho-'Alayhe-Wasallam) did promise us of Ghazwa-e-Hind. If I got chance to participate in it, then I would spend all my energy & wealth in it. If I got slained, then I would be considered among the most great martyrs. And if came back, then would be a freed Abu-Hurairah.
Imam Behqi (R) has also copied the same wordings in ‘As Sunan Al Kubra’. In his another narration, there is one addition. With the reference of Ibn-e-Daood, Masdad told about Abu-Ishaq Fazari that he used to say: ‘I wish that I could participate in the Ghazwat of Marbad (some place in East towards India from Arab), instead of all those Ghazwaat which I did in city Rome’.
Imam Behqi (R) has talked about the same narration in ‘Dalail un Nubuwwah’. And with his reference, this narration has been copied by Imam Syuti (R) in ‘Al Khasaais Al Kubra’.
Furthermore, the following Hadees quoters have narrated the same Hadees with a few word difference.
Sheikh Ahmad Shakir (R) approved the very Hadees.
Ibn e Kaseer copied in ‘Al Badaya Wa Nahaya’ from the testimonial of Imam Ahmad.
Abu Naeem (R) narrated it in ‘Huliyaat ul Auliya’.
Imam Hakim (R) remained silent after narrating this Hadees in ‘Al Mustadrak Al Saheeheen’. While, Imam Zahbi (R) omitted it from his Mustadrak.
Saeed bin Mansoor narrated it in his book ‘As Sunan’.
Khateeb Baghdadi wrote in the history of Baghdad that ‘I would make myself restless in it’.
Naeem bin Hammad; the teacher of Imam Bukhari (R) wrote in ‘Al Fitan’.
Ibn e Abi Asim (R) did in his book ‘Al-Jihad’.
Ibn e Abi Hatim (R) narrated in his book ‘Al Laal’ that ‘if I would be murdered, then would be alive by getting food (as shaheed) & if returned, then would be freed’.
Imam Bukhari (R) did narrate in ‘Al Tareekh Al Kabeer’
Imam Mazi did in ‘Tehzeeb ul Kamal’.
Ibn e Hajar Askalani did relate this Hadees in ‘Tehzeeb Al Tehzeeb’.
According to all the people written above, this Hadees is all correct and is beautiful.