On the authority of Abu Amr — who is also called Abu Amrah — Sufyan bin Abdullah ath- Thaqafee (may Allah be pleased with him) who said: I said,
“O Messenger of Allah, tell me something about Islam which I can ask of no one but you.” The Prophet (saw) said, “Say I believe in Allah — and then be steadfast.”
Sahih al-Muslim
From this hadith we can derive a couple of very important lessons. Firstly, those who fall into bidah (innovations) have greatly failed in the obligation of istiqamah (steadfastness). Istiqamah implies being upright along the straight Path. Those who follow bidah have chosen to go astray and swerve from the path that leads to Jannah. The rewards and benefits of staying upright on the faith are tremendous, and if one can manage to follow the Prophet’s (saw) example, surely Allah (swt) will be generous.
Imam al-Ghazali once said that the importance and necessity for istiqamah is so great that Allah (swt) has ordered His servants to recite Surah al-Fatihah in every rakah of their prayers. Surah al-Fatihah is so beautiful in that it contains a duah which is in essence a duah asking Allah (swt) to keep us steadfast. The duah is asking for continual guidance on the straight path.
“Guide us to the straight path”
Surah al-Fatihah, Ayah 6
Islam in itself is encompassed in two key aspects. The first aspect deals with having correct belief in Allah (swt). The second aspect is in remaining steadfast in the correct belief until death. And Allah (swt) knows best.