How can I establish myself in this life, in the grave, and in the Hereafter to avoid the trial of the grave, the questioning of the two angels, and the compression of the grave, based on Allah's saying: "Allah keeps firm those who believe, with the firm word, in worldly life and in the Hereafter"?

A servant remains steadfast and is saved from the horrors of the Barzakh (interim period between death and resurrection) and the Day of Judgment by persistently supplicating and resorting to Almighty Allah, asking Him for steadfastness, by adhering to obedience to Almighty Allah through preserving the obligatory duties and increasing supererogatory acts, and by continuously repenting and seeking forgiveness when committing acts that displease Him.