What is the ruling on supplicating in ruku’ when making an obligatory prayer? ما حكم الدعاء عند الركوع في صلاة الفرض؟

Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions.

As to what follows:

With regards to answering your question we say, success is by Allah Almighty.
With respect to supplicating in ruku’, Muslim narrated a hadith on the authority of Ibn Abas who said, The Messenger of Allah (peace be on him) said:
“As far as Ruk'u is concerned, exalt in it the Great and Glorious Lord, and while prostrating yourselves be earnest in supplication, for it is fitting that your supplications should be answered.”
This indicates that what is permissible in ruku’ is striving to exalt Allah by praising and glorifying Him. It indicates that prostration was specially made for supplication. This does not mean that one should not supplicate in ruku’, rather it means that supplication in sujood is more likely to be accepted than in any other position in Prayer.
Bukhari and Muslim  narrated a hadith  on the authority of Aisha (may Allah be pleased with her) who said:
“The Messenger of Allah (peace be on him) often said while bowing and prostrating himself; “Glory be to Thee, O Allah, out Lord.” And “Praise be to Thee, O Allah, forgive me,” Thus interpreting the (command in the Qur’an).
So a person making Prayer should strive to exalt the glorification of Allah while bowing and supplicate when in prostration

And Allah knows best.

Your brother,
Dr. Khalid al-Muslih
20 / 10 / 1424 AH