Rabbana lakal hamd in women's prayer

Question

I'm a woman, I want to know that it is compulsory to say rabbana lakal hamd after ruku in women's' namaz, somebody said to me it is important when you perform prayer with ja'mat, if you are praying alone, it is not important. and one more thing if you do not say 'rabbana lakal hamd' in prayer, will namaz valid?

Answer 1

A prayer is valid as long as you didn't miss fard or rukn act. These may differ from madhhab to madhhab to some extent. Ruku' itself is fard or rukn (depending on the standard technical term used by a madhhab) while standing afterwards is discussed the Malikis consider it fard. But what exactly you may say is to some extent open as it is sunnah.

But if you want to follow the sunnah of the prophet () you should recite one of the formulation he has thought us and among them is:

رَبَّنَا وَلَكَ الْحَمْد Rabbana wa laka l-Hamd. (with and without "wa")

As you may find, but other wordings are also mentioned:

• When the Prophet (ﷺ) said, "Sami`a l-lahu liman hamidah," (Allah heard those who sent praises to Him), he would say, "Rabbana wa laka l-hamd." On bowing and raising his head from it the Prophet (ﷺ) used to say Takbir. He also used to say Takbir on rising after the two prostrations. (See Hadith No. 656). ( Sahih al-Bukhari)

• When the Messenger of Allah (ﷺ) raised his back from the rukd' he pronounced: (سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ اللَّهُمَّ رَبَّنَا لَكَ الْحَمْدُ مِلْءَ السَّمَوَاتِ وَمِلْءَ الأَرْضِ وَمِلْءَ مَا شِئْتَ مِنْ شَىْءٍ بَعْدُ
  ‘Sami’ Allahu liman hamidah, Allahumma, Rabbana laka-l-hamd, mil’ as-samawati wa mil’ al- ard wa mil’ ma shi’ta min shay’in ba’d )
  Allah listened to him who praised Him. O Allah! our Lord! unto Thee be praise that would fill the heavens and the earth and fill that which will please Thee besides them. (Sahih Muslim)

• When the Messenger of Allah (ﷺ) raised his head after bowing, he said:
  (اللَّهُمَّ رَبَّنَا لَكَ الْحَمْدُ مِلْءَ السَّمَوَاتِ وَمِلْءَ الأَرْضِ وَمَا بَيْنَهُمَا وَمِلْءَ مَا شِئْتَ مِنْ شَىْءٍ بَعْدُ أَهْلَ الثَّنَاءِ وَالْمَجْدِ لاَ مَانِعَ لِمَا أَعْطَيْتَ وَلاَ مُعْطِيَ لِمَا مَنَعْتَ وَلاَ يَنْفَعُ ذَا الْجَدِّ مِنْكَ الْجَدُّ
  Allahumma Rabbana laka-l-hamd, mil’a as-samawati wa mil’a al- ard wa ma baynahuma wa mil’a ma shi’ta min shay’in ba’du, ahlu at-thnaa'i wal majdi la mani'a li ma a'atyta wa la mu'atiya li mamana'ata wa la yanfa'u dhal jaddi minka-l-Jaddu.)
  Allah! our Lord, to Thee be the praise that would fill the heavens and the earth and that which is between them, and that which will please Thee besides (them). Worthy art Thou of all praise and glory. No one can withhold what Thou givest, or give what Thou withholdest. And the greatness O! the great availeth not against Thee. (Sahih Muslim)

• When the Messenger of Allah (ﷺ) said: “ Allah listens to him who praises Him,” he also said: O Allah, our Lord, to thee be the praise in all heavens. Mu’ammil said( in his version); “ مِلْءَ السَّمَوَاتِ وَمِلْءَ الأَرْضِ وَمِلْءَ مَا شِئْتَ مِنْ شَىْءٍ بَعْدُ أَهْلَ الثَّنَاءِ وَالْمَجْدِ أَحَقُّ مَا قَالَ الْعَبْدُ وَكُلُّنَا لَكَ عَبْدٌ لاَ مَانِعَ لِمَا أَعْطَيْتَ
  (mil’ as-samawati wa mil’ al- ard wa mil’ ma shi’ta min shay’in ba’d, ahlu at-thana'i wal majdi ahhaqu ma qala al-'Abdu wa kulluna lak 'abdun, laa maani'a lima a'atayta. wa laa mu'tiya lima man'ata)
  In all the heavens, and in all the earth, and in all that it pleases Thee to create afterwards. O thou Who art worthy of praise and glory, most worthy of what a servant says, and we are all thy servants, no one can withhold what thou givest or give what Thou withholdest. “The narrators then were agreed on the words: “And riches cannot avail a wealthy person with Thee.” (Sunan abi Dawod -the translation here is incomplete, as it mixes statements of other narrators in the chain)

Note that what your friend said is wrong whatever you may say alone or in jama'at is the same the difference is in:

سَمِعَ اللَّهُ لِمَنْ حَمِدَه
Sami'a Allahu liman hamidah.

As in a congregation the imam would say (recite) it so you shouldn't do so and just answer:

The people behind the imam should not say: “Allah listens to him who praises Him.” But they should say: “ Our Lord, to Thee be the praise.” (Sunan abi Daowd)