Praise be to Allah.
The hadiths that speak of the conquest of India are as follows:
It was narrated that Thawbaan, the freed slave of the Messenger of Allah (blessings and peace of Allah be upon him), said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “There are two groups of my ummah whom Allah will protect from the Fire: a group who will conquer India, and a group who will be with ‘Eesaa ibn Maryam (peace be upon him).”
Narrated by an-Nasaa’i (no. 3175) and Imam Ahmad in al-Musnad (37/81), Mu’sasat ar-Risaalah edn. Classed as hasan by the commentators on al-Musnad. Classed as saheeh by al-Albaani in as-Silsilah as-Saheehah (no. 1934)
It was narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) promised us that we would conquer India, so if I am martyred I will be among the best of the martyrs, and if I return then I am Abu Hurayrah the freed (protected from Hellfire).
This hadith was narrated via three isnaads from Abu Hurayrah.
The first isnaad is from Jibr ibn ‘Ubaydah, from Abu Hurayrah
It was narrated by Imam Ahmad in al-Musnad (12/28) and others. This is a da‘eef (weak) isnaad because of Jibr ibn ‘Ubaydah. No one narrated from him except one narrator whose name was Sayyaar ibn al-Hakam, and no one regarded him as thiqah (trustworthy). Rather he was mentioned only in passing by Ibn Hibbaan in ath-Thiqaat. Hence Imam adh-Dhahabi said: It is not known who he was, and the report is odd. End quote.
See: Tahdheeb at-Tahdheeb (2/59).
The second isnaad is al-Bara’ ibn ‘Abdullah al-Ghanawi, from al-Hasan al-Basri, from Abu Hurayrah, who said:
My close friend, the truthful one, the Messenger of Allah (blessings and peace of Allah be upon him) told me: “Among this ummah there will be an expedition to Sindh and India.” If I live to see it and am martyred, all well and good, and if I – and he said some word – return, I am Abu Hurayrah the freed, I will be ransomed from the Fire.
Narrated by an-Nasaa’i in as-Sunan (no. 3173) and by Ahmad in al-Musnad (14/419). But it is also a da‘eef isnaad, because of al-Bara’ ibn ‘Abdullah al-Ghanawi concerning whom the critics were unanimously agreed that his hadith is layyin (a kind of weak hadith), as it says in Tahdheeb at-Tahdheeb (1/427). Moreover, there is an interruption in the isnaad between al-Hasan al-Basri and Abu Hurayrah (may Allah be pleased with him).
The third isnaad is Haashim ibn Sa‘eed, from Kinaanah ibn Nabeeh, from Abu Hurayrah.
This was narrated by Ibn Abi ‘Aasim in al-Jihaad (no. 247), but it is also a da‘eef isnaad because of Haashim ibn Sa‘eed, concerning whom Ibn Ma‘een said: He is nothing. Abu Haatim said: His hadith is da‘eef. See: Tahdheeb at-Tahdheeb (11/17).
The fourth isnaad is from Safwaan ibn ‘Amr, from one of his shaykhs, from Abu Hurayrah (may Allah be pleased with him), who said: The Messenger of Allah (blessings and peace of Allah be upon him) said – and he mentioned India – then he said: “An army of yours will invade India and Allah will grant its conquest to them, until they bring their kings in chains, and Allah will forgive them their sins. Then they will return and when they return, they will find the son of Maryam in ash-Shaam (Syria).” Abu Hurayrah said: If I live to see that campaign, I will sell everything I possess and join the campaign. Then if Allah grants us victory and we return, then I will be Abu Hurayrah the freed (protected from Hellfire). And when we return to Syria we will find there ‘Eesa ibn Maryam. Then I shall make sure that I draw close to him and tell him that I accompanied you, O Messenger of Allah. The Messenger of Allah (blessings and peace of Allah be upon him) smiled and said: “Unlikely, unlikely.” [very difficult?]
Narrated by Na‘eem ibn Hammaad in al-Fitan (p. 409). Its isnaad includes a narrator who was ambiguous about his narration from Abu Hurayrah. Its isnaad also includes Baqiyyah ibn al-Waleed who is mudallis and narrated by saying ‘an (“from”).
The third hadith is:
“Some people of my ummah will invade India and Allah will enable them to conquer it, until they bring the kings of India in chains, and Allah will forgive them their sins. Then they will return to ash-Shaam (Syria) and they will find ‘Eesa ibn Maryam in Syria.”
Narrated by Na‘eem ibn Hammaad in al-Fitan (p. 399). He said: al-Waleed told us, from Safwaan ibn ‘Amr, from someone who told him, from the Prophet (blessings and peace of Allah be upon him).
This isnaad is obviously da‘eef, because al-Waleed ibn Muslim narrated it by saying ‘an (“from”). It also appears to be mursal, because there is no indication that the one who told Safwaan ibn ‘Amr heard it from the Prophet (blessings and peace of Allah be upon him) or that he was a Sahaabi.
So to sum up: the hadith of Thawbaan is the one that is saheeh concerning the conquest of India. As for the hadith of Abu Hurayrah, most of its isnaads are da‘eef (weak). And Allah knows best.
What appears to be the case from the apparent meaning of the hadith of Thawbaan and the hadith of Abu Hurayrah – if it is saheeh – is that the conquest of India referred to will occur at the end of time, and at a time close to the descent of ‘Eesa ibn Maryam (peace be upon him), not at a time that was close to the era of Mu‘aawiyah ibn Abi Sufyaan (may Allah be pleased with him).
Al-Haafiz Ibn Katheer (may Allah be pleased with him) said:
The Muslims invaded India at the time of Mu‘aawiyah, in 44 AH, and there occurred things which will be explained below. It was also invaded by the great ruler Mahmoud ibn Sabuktagin, the ruler of Ghaznah who conquered India around 400 AH. He invaded the land, where he killed, took prisoners, and captured booty. He entered Somnath where he broke the greatest idol that they used to worship, and he captured its swords and necklaces. Then he returned, safe and victorious. End quote.
Al-Bidaayah wa’n-Nihaayah (6/223)
Hence al-‘Allaamah Hammood at-Tuwaijri (may Allah have mercy on him) said:
What is mentioned in the hadith of Abu Hurayrah (may Allah have mercy on him), which was narrated by Na‘eem ibn Hammaad, about the conquest of India has not happened up till now, but it will happen when ‘Eesaa ibn Maryam (peace be upon him) descends, if the hadith that says that is saheeh. And Allah knows best. End quote.
Ithaaf al-Jamaa‘ah (1/366)
And Allah knows best.